CN115549355A - Back-wound stator for motor, manufacturing method and high-speed permanent magnet motor - Google Patents

Abstract

The invention provides a back-wound stator for a motor, a manufacturing method and a high-speed permanent magnet motor, wherein the motor comprises a cylinder body, a retaining shoulder is formed on the cylinder body, and the back-wound stator comprises a stator iron core and a stator winding; the stator core is provided with a core main body, internal teeth and external teeth, the internal teeth are provided with internal winding grooves, and the external teeth are provided with external winding grooves; the stator winding is wound around the iron core main body, the inner side end of the stator winding is positioned in the inner winding slot, and the outer side end of the stator winding is positioned in the outer winding slot; the radial distance between the outer edge of the stator winding and the inner edge of the retaining shoulder is increased, so that a larger electrical gap is formed between the stator winding and the retaining shoulder, and short circuit accidents between the stator winding and the retaining shoulder are avoided; a second slot wedge is arranged in the spacing slot, and plays a role in radially limiting the first slot wedge, so that the first slot wedge is prevented from expanding outwards to be close to the barrel body and the retaining shoulder; the second slot wedge blocks the spacing slot, so that cooling gas is forced to flow from the air gap between the stator and the rotor, and the cooling performance deterioration caused by the change of a cooling flow channel is avoided.

Description

Back-wound stator for motor, manufacturing method and high-speed permanent magnet motor

Technical Field

The invention belongs to the technical field of motors, and particularly relates to a back-wound stator for a motor, a manufacturing method and a high-speed permanent magnet motor.

Background

With the rapid development of economic society in China, more and more occasions are applied to high-speed permanent magnet motors, such as air compressors, high-speed machine tools, vacuum pumps and the like; the motor has the advantages of high power density, high efficiency, quick dynamic response and small size, and has the advantages of energy conservation, emission reduction and the like; in the field of high-speed permanent magnet motors, in order to reduce harmonic waves generated during the operation of the motors, distributed stator windings are usually adopted for stators, but the end parts of the distributed stator windings are high, so that the axial length value of the motor is large, a rotor is slender, and the critical rotating speed is low; the back-wound stator structure can obviously shorten the end size of the stator winding, thereby saving the valuable axial space of the motor and widening the limit rotating speed of the high-speed permanent magnet motor;

however, in the existing high-speed permanent magnet motor, the radial thickness of the outer yoke part of the outer teeth of the stator core is small, so that the distance between the stator winding and the blocking shoulder of the motor cylinder is too short, the electric gap is small, and short-circuit accidents are easy to happen; in addition, the slot wedge which has a limiting effect on the stator winding interferes with the retaining shoulder of the motor cylinder, so that the stator is easily not assembled in place.

Disclosure of Invention

In view of the above, the invention provides a back-wound stator for a motor, a manufacturing method thereof and a high-speed permanent magnet motor, so as to solve the problems that in the prior art, the radial thickness of an outer yoke part of outer teeth of a stator core is small, short circuit is easy to occur between a stator winding and a retaining shoulder, the stator is not assembled in place, and the like.

The invention provides a back-wound stator for a motor, which comprises a barrel, wherein a retaining shoulder is formed on the barrel, the back-wound stator is arranged on the radial inner side of the barrel, and the retaining shoulder has a limiting effect on the back-wound stator; the back-wound stator comprises a stator core and a stator winding; the stator core is provided with a core main body, internal teeth and external teeth, the internal teeth are arranged on the radial inner side of the core main body and are provided with internal winding grooves, and the external teeth are arranged on the radial outer side of the core main body and are provided with external winding grooves; the stator winding is wound around the iron core main body, the inner side end of the stator winding is positioned in the inner winding slot, and the outer side end of the stator winding is positioned in the outer winding slot;

the radial distance between the outer edge of the stator winding and the inner edge of the retaining shoulder is delta h = h1-h0 and is more than or equal to 5mm, wherein h1 is the distance between the outer edge of the stator winding and the inner wall of the cylinder, and h0 is the radial thickness of the retaining shoulder.

Further optionally, the outer teeth comprise an outer neck portion and an outer yoke portion, the outer yoke portion is connected with the outer edge of the core body through the outer neck portion, and the outer winding slot is formed between the outer yoke portion and the outer edge of the core body;

the back-wound stator further comprises a first slot wedge disposed between the outer yoke and the stator windings;

the radial thickness of the outer yoke part is h2, the radial thickness of the first slot wedge is h3, h2+ h3 is more than or equal to 5mm, and h2 is more than or equal to h0.

Further optionally, the external teeth comprise a plurality of external teeth, and the plurality of external teeth are arranged along the circumferential direction of the iron core main body; the outer yoke part comprises a first end and a second end, and the first end and the second end are oppositely arranged on two sides of the outer neck part along the circumferential direction of the iron core main body; in two adjacent outer yokes, a first outer winding sub-slot is formed between the first end of one outer yoke and the outer edge of the core body, and a second outer winding sub-slot is formed between the second end of the other outer yoke and the outer edge of the core body; the first outer winding subslot and the second outer winding subslot are communicated with each other to form the outer winding slot;

in two adjacent outer yokes, a spacing groove is formed between the second end of one outer yoke and the first end of the other outer yoke, and the spacing groove is communicated with an outer winding groove;

the back-wound stator further comprises a second slot wedge disposed within the spacer slot.

Further optionally, the spacing slot is formed with a first notch and a second notch, and the first notch and the second notch are oppositely arranged along the radial direction of the core main body; the spacing groove is communicated with the outer winding groove through the first notch;

the circumferential width of the first notch is a1, the circumferential width of the second notch is a2, a1 is greater than a2, and a2 is related to the outer diameter and the number of slots of the back-wound stator.

Further optionally, a2 < 1.5 × a1.

Further optionally, the structure of the second slot wedge is adapted to the structure of the spacing slot, and the radial thickness of the second slot wedge is h4, and h4 < h2.

Further optionally, the second slot wedge is disposed near the outlet end of the back-wound stator, and the second slot wedge is located axially inward of the outlet end of the back-wound stator.

Further optionally, the axial length of the stator core is c1, and the axial length of the second slot wedge is c2, such that-0.5 × c1 ≦ 0.5 × c1-c2 ≦ 0.

The invention also provides a method for manufacturing a back-wound stator, which is any one of the back-wound stators for the motor, and the method comprises the following steps:

s1, winding the stator winding around the iron core main body in the inner winding groove and the outer winding groove;

s2, arranging the first slot wedge between the outer yoke and a stator winding;

s3, arranging the second slot wedge in the spacing slot;

and S4, performing paint dipping or glue pouring treatment on the back-wound stator.

The invention also provides a high-speed permanent magnet motor, which comprises the back-wound stator for the motor or a manufacturing method adopting the back-wound stator.

Compared with the prior art, the invention has the following beneficial effects:

(1) The radial distance between the outer edge of the stator winding and the inner edge of the retaining shoulder is increased by thickening the radial thickness of the outer yoke part of the outer teeth, so that a larger electrical gap is formed between the stator winding and the retaining shoulder, the insulation distance between the stator winding and the retaining shoulder is prolonged, and short circuit accidents between the stator winding and the retaining shoulder are avoided; the distance between the first slot wedge and the blocking shoulder is increased, so that an assembly space is formed between the stator and the barrel, the stator can be accurately assembled in the barrel, the assembly precision of the stator is high, and the problem that the stator is not assembled in place due to interference between the first slot wedge and the blocking shoulder is solved;

(2) The second slot wedges are arranged in the spacing slots, and play a role in radially limiting the first slot wedges, so that the first slot wedges are prevented from expanding outwards to be close to the barrel body and the retaining shoulders; the spacing slot is designed to be a trapezoidal structure with a narrow outer part and a wide inner part, the second slot wedge is pressed against the spacing slot by the outward expansion force of the stator winding, the second slot wedge is initially fixed through friction force, and the second slot wedge is completely fixed through subsequent paint invasion or glue filling treatment;

(3) The second slot wedge strengthens the insulating strength between the stator winding and the blocking shoulder, and the second slot wedge blocks the spacing slot, so that cooling gas is forced to flow from the air gap between the stator and the rotor, and the cooling performance deterioration caused by the change of a cooling flow channel is avoided.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structures, the proportions, the sizes, and the like shown in the specification are only used for matching with the contents disclosed in the specification, so that those skilled in the art can understand and read the present invention, and do not limit the conditions for implementing the present invention, so that the present invention has no technical essence, and any modifications of the structures, changes of the proportion relation, or adjustments of the sizes, should still fall within the scope of the technical contents disclosed in the present invention without affecting the efficacy and the achievable purpose of the present invention.

Fig. 1 is a schematic structural diagram of a stator core according to an embodiment of the present invention;

FIG. 2a is a schematic structural diagram of a back-wound stator according to an embodiment of the present invention;

FIG. 2b is a schematic view of an assembly structure of a back-wound stator and a cylinder according to an embodiment of the present invention;

FIGS. 3a, 3b, 3c and 3d are schematic views of partial structures of back-wound stators (including dimensions) according to embodiments of the present invention;

in the figure:

1-a stator core; 11-a core body; 12-external teeth; 121-outer neck; 122-outer yoke; 123-a first end; 124-a second end; 13-outer winding slots; 14-a spacer groove; 141-a first notch; 142-a second notch; 15-internal teeth; 16-inner winding slots;

2-stator winding; 31-a first wedge; 32-a second wedge; 4-shoulder blocking; 5-cylinder body.

Detailed Description

The present invention is described in terms of particular embodiments, other advantages and features of the invention will become apparent to those skilled in the art from the following disclosure, and it is to be understood that the described embodiments are merely exemplary of the invention and that it is not intended to limit the invention to the particular embodiments disclosed. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the examples of the invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "the plural" typically includes at least two, but does not exclude the presence of at least one.

It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a good or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such good or system. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in articles of commerce or systems including such elements.

In the existing high-speed permanent magnet motor, the radial thickness of an outer yoke part of the outer teeth of a stator core is small, so that the distance between a stator winding and a blocking shoulder of a motor cylinder is too short, the electric gap is small, and short-circuit accidents are easy to happen; in addition, the slot wedge which has a limiting effect on the stator winding is interfered with the retaining shoulder of the motor cylinder, so that the stator is easy to be assembled in place;

the invention creatively provides a back-wound stator for a motor, which comprises a cylinder body, wherein a shoulder is formed on the cylinder body, and the back-wound stator is arranged on the radial inner side of the cylinder body; the back-wound stator comprises a stator core and a stator winding; the stator core is provided with a core main body, internal teeth and external teeth, the internal teeth are arranged on the radial inner side of the core main body and provided with internal winding grooves, and the external teeth are arranged on the radial outer side of the core main body and provided with external winding grooves; the stator winding is wound around the iron core main body, the inner side end of the stator winding is positioned in the inner winding slot, and the outer side end of the stator winding is positioned in the outer winding slot; the radial distance between the outer edge of the stator winding and the inner edge of the retaining shoulder is delta h = h1-h0 which is more than or equal to 5mm, wherein h1 is the distance between the outer edge of the stator winding 2 and the inner wall of the cylinder 5, and h0 is the radial thickness of the retaining shoulder 4;

increasing delta h to enable a larger electrical gap to be formed between the stator winding and the retaining shoulder, prolonging the insulation distance between the stator winding and the retaining shoulder and avoiding short circuit accidents between the stator winding and the retaining shoulder; the stator and the barrel are provided with an assembly space, the stator can be accurately assembled in the barrel, the stator is high in assembly precision, and the problem that the stator is not assembled in place is solved.

Further, as shown in fig. 1, the internal teeth 15 include an inner neck portion and an inner yoke portion, the inner yoke portion is connected to the inner edge of the core main body 11 through the inner neck portion, and an inner winding slot 16 is formed between the inner yoke portion and the inner edge of the core main body 11; the external teeth 12 include an outer neck portion 121 and an outer yoke portion 122, the outer yoke portion 122 is connected to the outer edge of the core body 11 through the outer neck portion 121, and an outer winding slot 13 is formed between the outer yoke portion 122 and the outer edge of the core body 11;

as shown in fig. 2a, 2b and 3c, the back-wound stator further includes a first slot wedge 31, the first slot wedge 31 is disposed between the outer yoke 122 and the stator winding 2, and acts as a limit for the stator winding 2, so as to avoid the problem of electrical short circuit caused by the stator winding 2 expanding outwards to be close to the cylinder 5 and the shoulder 4;

as shown in fig. 3a, 3b and 3d, the radial thickness of the outer yoke 122 is h2, the radial thickness of the first slot wedge 31 is h3, and h2+ h3 is ≧ 5mm, and h2 ≧ h0; therefore, h2 or h3 can be increased to increase Δ h; preferably, h2 is increased, so that the insulating strength between the stator winding 2 and the retaining shoulder 4 can be improved, the distance between the first slot wedge 31 and the retaining shoulder 4 is increased, the first slot wedge 31 can not interfere with the retaining shoulder 4 any more, the coil of the stator winding 2 is prevented from expanding outwards to be close to the retaining shoulder 4, an assembly space is formed between the stator and the barrel 5, the stator can be accurately assembled in the barrel, the assembly precision of the stator is high, and the problem that the stator is not assembled in place due to the interference between the first slot wedge 31 and the retaining shoulder 4 is solved;

it should be noted that h2 may be set according to actual conditions, and is generally larger than the radial thickness of the stop shoulder 4 compared to the radial thickness of the outer yoke portion 122.

As shown in fig. 1, the external teeth 12 include a plurality of external teeth 12, and the plurality of external teeth 12 are arranged along the circumferential direction of the core main body 11; the outer yoke portion 122 includes a first end 123 and a second end 124, the first end 123 and the second end 124 being oppositely disposed on both sides of the outer neck portion 121 in the circumferential direction of the core body 11; of the two adjacent outer yoke portions 122, a first outer winding sub-slot is formed between the first end 123 of one outer yoke portion 122 and the outer edge of the core body 11, and a second outer winding sub-slot is formed between the second end 124 of the other outer yoke portion 122 and the outer edge of the core body 11; the first outer winding subslot is communicated with the second outer winding subslot to form an outer winding slot 13; the first wedges 31 include a plurality of first wedges 31, each first wedge 31 being disposed between the corresponding outer yoke 122 and the stator winding 2;

in two adjacent outer yoke portions 122, a spacing groove 14 is formed between the second end 124 of one outer yoke portion 122 and the first end 123 of the other outer yoke portion 122, and the spacing groove 14 is communicated with the outer winding groove 13;

as shown in fig. 2a, 2b and 3c, in order to solve the problem that the first slot wedge 31 is not firmly fixed and is easily contacted with the blocking shoulder 4, the present embodiment proposes that the back-wound stator further comprises a second slot wedge 32, and the second slot wedge 32 is disposed in the spacing slot 14; the second slot wedge 32 has a radial limiting effect on the first slot wedge 31, and the first slot wedge 31 and the stator winding 2 are prevented from expanding outwards to be close to the cylinder 5 and the retaining shoulder 4; in addition, the first slot wedge 31 and the second slot wedge 32 separate the stator winding 2 from the shoulder 4, so that an insulation effect is achieved, and the insulation strength between the stator winding 2 and the shoulder 4 is improved;

further, the spacing slot 14 is designed to be a trapezoidal structure with a narrow outer part and a wide inner part, the second slot wedge 32 is pushed against the spacing slot 14 by the outward expansion force of the stator winding 2, the second slot wedge 32 is preliminarily fixed by the friction force between the wall surface of the spacing slot 14 and the wall surface of the second slot wedge 32, and the second slot wedge 32 is completely fixed by subsequent paint invasion or glue filling treatment; specifically, the spacing slot 14 is formed with a first notch 141 and a second notch 142, the first notch 141 and the second notch 142 being disposed opposite to each other in the radial direction of the core main body 11; the partition groove 14 communicates with the outer winding groove 13 through the first notch 141;

as shown in fig. 3b, the circumferential width of the first notch 141 is a1, the circumferential width of the second notch 142 is a2, a1 > a2, and a2 is related to the outer diameter and the number of slots of the back-wound stator; the circumferential width of the first notch 141 and the circumferential width of the second notch 142 are both smaller than the circumferential width of the outer winding groove 13; both the design of a1 and a2 have certain requirements, a1 is not too large, otherwise, the stressed area of the first slot wedge 31 is smaller, and the middle part of the first slot wedge 31 is easy to deform under stress; a2 is not suitable to be too small, otherwise, the coil inserting efficiency of the stator is reduced;

preferably, a1 < 1.5 a2.

As shown in fig. 3b and 3d, in addition, in order to solve the problem that the radial thickness of the second slot wedge 32 is too large, and interference with the barrel 5 is likely to cause the stator to be assembled improperly, the embodiment designs the structure of the second slot wedge 32 to be matched with the structure of the spacing slot 14, and the radial thickness of the second slot wedge 32 is h4, and h4 is less than h2; specifically, the radial thickness of the second slot wedge 32 is slightly smaller than that of the outer yoke 122, so that the second slot wedge 32 blocks the air duct of the spacing slot 14, but does not exceed the outer edge of the outer yoke 122, otherwise the stator interferes with the barrel 5 when the stator is assembled;

the second slot wedges 32 strengthen the insulation strength between the stator winding 2 and the blocking shoulder 4, the second slot wedges 32 block the spacing slots 14, cooling gas is forced to flow from the air gap between the stator and the rotor, and the cooling performance deterioration caused by the change of a cooling flow channel is avoided.

To the unreasonable problem that leads to back-wound stator assembly not in place that sets up in second slot wedge 32 position, this embodiment proposes, and second slot wedge 32 is close to the leading-out terminal setting of back-wound stator, and second slot wedge 32 is located the axial inboard of the leading-out terminal of back-wound stator, and second slot wedge 32 does not surpass the terminal surface of the iron core main part 11 that corresponds after the assembly, assembles the problem that the assembly is not in place when avoiding the stator to assemble the barrel inboard.

Preferably, the axial length of the stator core 1 is c1 and the axial length of the second slot wedge 32 is c2, such that-0.5 × c1 ≦ 0.5 × c1-c2 ≦ 0; c2 is designed with certain requirements, c2 is not too large, and after the second slot wedge 32 is assembled, the end face of the second slot wedge 32 at the wire outlet end of the stator should not exceed the end face of the iron core main body 11, otherwise, the problem that the stator is not assembled in place can be caused; furthermore, c2 should not be too small, otherwise it is difficult to assemble the second wedge 32.

The present invention also provides a method for manufacturing a back-wound stator, where the back-wound stator is any one of the above back-wound stators for an electric machine, and the method includes:

s1, winding a stator winding 2 in an inner winding slot 16 and an outer winding slot 13 around an iron core main body 11 when the stator is off-line; specifically, the inside end of the stator winding 2 is located in the inner winding slot 16, and the outside end of the stator winding 2 is located in the outer winding slot 13;

s2, disposing the first slot wedge 31 between the corresponding outer yoke portion 122 and the stator winding 2;

s3, arranging the second slot wedges 32 in the corresponding spacing slots 14; after the winding of the stator winding 2 is finished, the stator winding 2 is compressed by the first slot wedge 31, the stator winding 2 tends to expand towards the outer side far away from the iron core main body 11, and after the first slot wedge 31 is compressed by the second slot wedge 32, the first slot wedge 31 can press the second slot wedge 32 in the spacing slot 14, so that the preliminary fixing of the second slot wedge 32 is realized;

and S4, when the stator is off-line, performing paint dipping or glue pouring treatment on the back-wound stator, and completely fixing the second slot wedge 32 by using insulating paint or pouring glue.

The present invention also provides a motor, including any one of the above back-wound stators for motors or a manufacturing method using the above back-wound stator; the back-wound stator can obviously shorten the end size of the stator winding 2 of the motor, thereby saving the valuable axial space of the motor and widening the limit rotating speed of the high-speed permanent magnet motor.

Exemplary embodiments of the present disclosure are specifically illustrated and described above. It is to be understood that the present disclosure is not limited to the precise arrangements, instrumentalities, or instrumentalities described herein; on the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (10)

1. A back-wound stator for a motor comprises a barrel (5), wherein a retaining shoulder (4) is formed on the barrel (5), the back-wound stator is arranged on the radial inner side of the barrel (5), and the retaining shoulder (4) has a limiting effect on the back-wound stator; the back-wound stator is characterized by comprising a stator iron core (1) and a stator winding (2); the stator core (1) is provided with a core main body (11), internal teeth (15) and external teeth (12), the internal teeth (15) are arranged on the radial inner side of the core main body (11) and are provided with internal winding grooves (16), and the external teeth (12) are arranged on the radial outer side of the core main body (11) and are provided with external winding grooves (13); the stator winding (2) is wound around the iron core main body (11), the inner side end of the stator winding (2) is positioned in the inner winding slot (16), and the outer side end of the stator winding (2) is positioned in the outer winding slot (13);

the radial distance between the outer edge of the stator winding (2) and the inner edge of the retaining shoulder (4) is delta h = h1-h0 and is more than or equal to 5mm, wherein h1 is the distance between the outer edge of the stator winding (2) and the inner wall of the cylinder (5), and h0 is the radial thickness of the retaining shoulder (4).

2. The back-wound stator for electric motor according to claim 1, wherein the outer teeth (12) comprise an outer neck portion (121) and an outer yoke portion (122), the outer yoke portion (122) being connected with an outer edge of the core body (11) through the outer neck portion (121), the outer yoke portion (122) and the outer edge of the core body (11) forming the outer winding slot (13) therebetween;

the back-wound stator further comprises a first wedge (31), the first wedge (31) being arranged between the outer yoke (122) and a stator winding (2); the radial thickness of the outer yoke portion (122) is h2, the radial thickness of the first slot wedge (31) is h3, h2+ h3 is more than or equal to 5mm, and h2 is more than or equal to h0.

3. The back-wound stator for electric motor according to claim 2, wherein the external teeth (12) comprise a plurality of external teeth (12) arranged along a circumferential direction of the core main body (11); the outer yoke part (122) comprises a first end (123) and a second end (124), and the first end (123) and the second end (124) are oppositely arranged on two sides of the outer neck part (121) along the circumferential direction of the iron core main body (11); a first outer winding sub-slot is formed between the first end (123) of one outer yoke part (122) and the outer edge of the iron core body (11) and a second outer winding sub-slot is formed between the second end (124) of the other outer yoke part (122) and the outer edge of the iron core body (11) in two adjacent outer yoke parts (122); the first outer winding subslot and the second outer winding subslot are communicated with each other and form the outer winding slot (13);

in two adjacent outer yoke parts (122), a spacing groove (14) is formed between the second end (124) of one outer yoke part (122) and the first end (123) of the other outer yoke part (122), and the spacing groove (14) is communicated with an outer winding groove (13);

the back wound stator further comprises a second wedge (32), the second wedge (32) being arranged within the spacer groove (14).

4. The back-wound stator for electric motor according to claim 3, wherein the spacing slot (14) is formed with a first notch (141) and a second notch (142), the first notch (141) and the second notch (142) being oppositely disposed in a radial direction of the core main body (11); the spacing groove (14) is communicated with the outer winding groove (13) through the first notch (141);

the circumferential width of the first notch (141) is a1, the circumferential width of the second notch (142) is a2, a1 is greater than a2, and a2 is related to the outer diameter and the number of slots of the back-wound stator.

5. The back-wound stator for an electrical machine according to claim 4, wherein a1 < 1.5 a2.

6. Back-wound stator for an electrical machine according to claim 3, characterized in that the structure of the second slot wedge (32) is adapted to the structure of the spacing slot (14) and the radial thickness of the second slot wedge (32) is h4, and h4 < h2.

7. The back-wound stator for an electric machine according to claim 3, characterized in that the second wedge (32) is arranged close to the outlet end of the back-wound stator and the second wedge (32) is located axially inside the outlet end of the back-wound stator.

8. A back-wound stator for an electrical machine according to claim 7, characterized in that the axial length of the stator core (1) is c1 and the axial length of the second slot wedge (32) is c2, satisfying-0.5 × c1 ≦ 0.5 × c1-c2 ≦ 0.

9. A method of manufacturing a back-wound stator, wherein the back-wound stator is the back-wound stator for an electric machine according to any one of claims 3 to 8, the method comprising:

s1, winding the stator winding (2) around the iron core main body (11) in the inner winding groove (16) and the outer winding groove (13);

s2, arranging the first slot wedges (31) between the corresponding outer yokes (122) and stator windings (2);

s3, arranging the second slot wedges (32) in the corresponding spacing slots (14);

and S4, performing paint dipping or glue pouring treatment on the back-wound stator.

10. A high speed permanent magnet machine comprising a back-wound stator for an electrical machine according to any of claims 1 to 8 or a method of manufacturing a back-wound stator according to claim 9.

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