CN111697726B

CN111697726B - Rotor of motor and motor

Info

Publication number: CN111697726B
Application number: CN202010592307.0A
Authority: CN
Inventors: 高东东; 吴广荣; 刘佳佳; 马梓净; 赵旭敏
Original assignee: Gree Green Refrigeration Technology Center Co Ltd of Zhuhai
Current assignee: Gree Green Refrigeration Technology Center Co Ltd of Zhuhai
Priority date: 2020-06-24
Filing date: 2020-06-24
Publication date: 2021-11-05
Anticipated expiration: 2040-06-24
Also published as: CN111697726A

Abstract

The invention relates to a rotor of a motor and the motor, wherein the rotor is of an embedded rotor structure and comprises a rotor core, a plurality of extending parts and a plurality of magnetic parts, the extending parts of the rotor core are arranged in a section vertical to the central axis of the rotor core, and the section of the top surface of the rotor core is in a multi-section arc shape; meanwhile, the problems of large cogging torque and poor running stability of the motor, and large rotation speed fluctuation especially when the motor runs at low speed can be solved; the motor has the advantages that the problem of large motor torque pulsation and large cogging torque is solved, the stray loss of the motor can be reduced, and the motor efficiency is improved.

Description

Rotor of motor and motor

Technical Field

The invention relates to the field of electric appliances, in particular to a rotor of a motor and the motor.

Background

The permanent magnet motor has simple structure, reliable operation, small size, light weight and good operation performance, and is widely applied to refrigeration compressors. The permanent magnet motor can be divided into a surface type permanent magnet motor and a built-in type permanent magnet motor according to different positions of the magnetic steel on the rotor, the surface type permanent magnet motor can be divided into a convex type permanent magnet motor and a built-in type permanent magnet motor according to different magnetic circuit structures of the rotor, and a rotor part of the surface embedded type permanent magnet motor comprises an iron core extending part.

The surface embedded permanent magnet motor has the advantages of simple manufacturing process and low manufacturing cost, can fully utilize reluctance torque generated by asymmetry of a rotor magnetic circuit, effectively improves the power density and the motor efficiency of the motor, has better dynamic performance than a surface convex permanent magnet motor, but has larger torque pulsation and tooth space torque, can influence the starting and running of the motor due to overlarge torque pulsation, generates larger vibration and noise, is not favorable for controlling the driving stability due to larger tooth space torque, and particularly influences the low-speed running stability of the motor and the high-precision positioning in position control. Reducing the torque ripple of surface-embedded permanent magnet motors is therefore an important consideration and solution in motor design.

Chinese patent document CN104795909A discloses a surface-embedded permanent magnet motor structure for an air compressor, which has a compact structure, a high rotation speed, a high mechanical strength, and a small harmonic loss, and this patent focuses on explaining that the surface-embedded permanent magnet motor can effectively increase the mechanical strength of a rotor by using a wedge-shaped groove, and does not describe the length of the wedge-shaped groove and the relationship between the length of the wedge-shaped groove and the thickness of magnetic steel.

Disclosure of Invention

In view of this, the present invention provides a rotor of a motor and a motor, by setting a relationship between a length of an extension portion and a thickness of a magnetic member; and/or by providing the shape of the surface of the projection; and/or, by arranging grooves on both sides of the protruding part and by arranging the shape of the grooves; the problem that the existing motor is large in torque pulsation is solved.

Specifically, the method comprises the following steps: a rotor of an electric machine comprising: the rotor comprises a rotor core and a plurality of magnetic pieces, wherein a plurality of extending parts are formed on the rotor core in the circumferential direction, the plurality of extending parts radially protrude out of the circumferential surface of the rotor core, one magnetic piece is arranged between every two adjacent extending parts of the plurality of extending parts, and the plurality of magnetic pieces are alternately arranged along the circumferential direction of the rotor core according to N-S poles; the section of the top surface (outer surface) of the magnetic part in the section perpendicular to the central axis of the rotor core is a first circular arc, and the circular arc radius of the first circular arc is R1; the section of the inner surface of the magnetic part in the section perpendicular to the central axis of the rotor core is a second circular arc, and the circular arc radius of the second circular arc is R2; the thickness of the magnetic element is R1-R2; the section of the top surface of the extension part of the rotor core is a third circular arc in the section perpendicular to the central axis of the rotor core, and the radius of the third circular arc is R3; the length of the extension is h, h is R3-R2; wherein h is (0.3-0.7) × (R1-R2).

Preferably, in a cross section of the rotor core perpendicular to the central axis of the rotor core, the cross section of the top surface of the rotor core is a fourth circular arc, and the radius of the fourth circular arc is R4; the first arc, the second arc, the third arc and the fourth arc are concentrically arranged, and R4 is R2.

Preferably, the following components: h is 0.5 (R1-R2).

Preferably, each of the plurality of magnetic members occupies a circumferential angle δ in the circumferential direction of the rotor core, and each of the protruding portions occupies a circumferential angle θ in the circumferential direction of the rotor core, where δ and θ satisfy the relation δ + θ of 90 °.

Preferably, 1/8 Δ ≦ θ ≦ 1/2 Δ.

Preferably, θ is 18 ° and δ is 72 °.

Preferably, a plurality of protruding portions are uniformly distributed on the circumference of the rotor core.

Preferably, the protruding portion of the rotor core has a cross section perpendicular to the central axis of the rotor core, and the cross section of the top surface of the protruding portion is a multi-segment circular arc.

Preferably, two sides of part or all of the plurality of extending parts are provided with grooves.

Preferably, the rotor is a built-in rotor structure.

In addition, the present invention also provides a rotor of a motor, comprising: the rotor comprises a rotor core, a plurality of extending parts and a plurality of magnetic parts, wherein the plurality of extending parts are distributed on the periphery of the rotor core; the extension part of the rotor core is in the section vertical to the central axis of the rotor core, and the section of the top surface of the extension part is a multi-segment line.

Preferably, the multi-segment line segment is formed in a wave shape.

Preferably, each segment of the multi-segment line segment is a circular arc.

Preferably, the number of the segments of the multi-segment line segment is 2-5, the radiuses of the circular arcs of the multi-segment circular arc are all the same, and the radiuses are marked as Rs.

Preferably, the length of the plurality of extending parts extending out of the rotor core is recorded as h, wherein the Rs is more than or equal to 0 and less than or equal to 3/4.

Preferably, Rs 1/2 xh.

Preferably, the center O' of each arc of the multi-segment circular arc is on a bisector of the extension width, and the number n of the bisectors is determined by the number m of the multi-segment circular arc segments, and satisfies the relation n-2 × m-1.

Preferably, the grooves have a cross-sectional shape in a cross-section perpendicular to the central axis of the rotor core, the cross-sectional shape being a single semicircle or an equilateral triangle or a double semicircle.

In addition, the present invention provides a rotor of an electric motor, including: the rotor comprises a rotor core, a plurality of extending parts and a plurality of magnetic pieces, wherein the plurality of extending parts are distributed on the circumference of the rotor core, each magnetic piece of the plurality of magnetic pieces is arranged between two adjacent extending parts, and the plurality of magnetic pieces are alternately arranged according to N-S poles along the circumference of the rotor core; grooves are formed in two sides of part or all of the extending parts.

Preferably, the grooves are used to reduce torque ripple of the motor.

Preferably, the plurality of protruding portions are evenly distributed in the circumferential direction of the rotor core.

Preferably, two side edges of the protruding part are in a section perpendicular to the central axis of the rotor core, and the section is a straight line; the cross section of the groove is in the shape of a single semicircle, and the circle center of the single semicircle is located at the middle point of the straight line of the cross sections of the two sides of the extension part.

Preferably, the length of the protruding part protruding out of the rotor core is recorded as h, the radius of the single semicircle is r1, wherein 1/8 & lth & gt r1 & lth & gt 3/8 & lth & gt,

preferably, wherein r1 ═ 1/2 × h.

Preferably, two side edges of the protruding part are in a section perpendicular to the central axis of the rotor core, and the section is a straight line; the cross section of the groove is triangular, and the middle point of the bottom edge of the triangle is positioned on the middle point of the straight lines of the cross sections at the two sides of the extension part.

Preferably, the triangle is an equilateral triangle with side length r2, wherein 1/8 h ≦ r2 ≦ 3/8 h.

Preferably, two side edges of the protruding part are in a section perpendicular to the central axis of the rotor core, and the section is a straight line; the cross section of the groove is in a double semicircle shape, and the circle centers of the double semicircle are respectively located at the 1/4 point position and the 3/4 point position of the straight line on the cross section of the two sides of the extension part.

Preferably, the length of the protruding portion protruding from the rotor core is denoted by h, the radius of the double semi-circle is the same, and the radius is denoted by r3, where r3 is 1/4 × h.

In addition, the invention further provides a motor, and the motor comprises the rotor of the motor.

Preferably, the motor is a permanent magnet motor.

According to the embodiment of the invention, through the arrangement, the torque pulsation of the motor can be obviously reduced, the noise of the motor is reduced, the cogging torque of the motor is improved, the running stability of the motor is improved, the stray loss of the motor is reduced, and the efficiency of the motor can be improved.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings. The drawings described below are merely some embodiments of the present disclosure, and other drawings may be derived from those drawings by those of ordinary skill in the art without inventive effort.

Fig. 1 is a schematic perspective view of a rotor of a motor according to a first embodiment of the present invention.

Fig. 2 is a schematic perspective view of a rotor core according to a first embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view of a motor according to a first embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view of a rotor core according to a first embodiment of the present invention.

Fig. 5 is a schematic diagram comparing torque ripple of a motor using a rotor according to a first embodiment of the present invention with that of a motor of the prior art.

Fig. 6 is a schematic cross-sectional view of a rotor core according to a second embodiment of the present invention.

Fig. 7 is a schematic diagram showing a comparison of torque ripple between a motor using a rotor according to a second embodiment of the present invention and a motor using a rotor according to a first embodiment of the present invention.

Fig. 8 is a schematic cross-sectional view of a rotor core according to a third embodiment of the present invention.

Fig. 9 is a second schematic cross-sectional view of a rotor core according to a third embodiment of the present invention.

Fig. 10 is a third schematic sectional view of a rotor core according to a third embodiment of the present invention.

Fig. 11 is a schematic diagram showing a torque ripple comparison between a motor using a rotor (a groove having a single semicircular shape) according to a third embodiment of the present invention and a motor of the related art.

Fig. 12 is a schematic diagram showing a comparison of torque ripple between a motor using a rotor (groove shape is equilateral triangle) according to the third embodiment of the present invention and a motor of the prior art.

Fig. 13 is a schematic diagram showing a torque ripple comparison between a motor using a rotor (groove shape is a double semicircle) according to the third embodiment of the present invention and a motor according to the prior art.

Wherein: 1-rotor core, 11-through hole, 12-extension part, 13-groove, 2-magnetic part, 3-stator, 31-tooth space;

a 0-torque ripple curve of existing motor, a 1-torque ripple curve of motor using rotor of motor of the first embodiment of the present invention; a2 — torque ripple curve of the motor using the rotor of the motor of the second embodiment of the present invention; a 31-torque ripple curve of the motor using the rotor (groove is single semicircle) of the motor of the third embodiment of the present invention; a 32-torque ripple curve of the motor using the rotor (grooves are triangular) of the motor according to the third embodiment of the present invention; a 33-torque ripple curve of motor using rotor (groove is double semicircle) of motor of the third embodiment of the present invention.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals denote the same or similar parts in the drawings, and thus, a repetitive description thereof will be omitted.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the subject matter of the present disclosure can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the disclosure.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various structures, these structures should not be limited by these terms. These terms are used to distinguish one structure from another structure. Thus, a first structure discussed below may be termed a second structure without departing from the teachings of the disclosed concept. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It is to be understood by those skilled in the art that the drawings are merely schematic representations of exemplary embodiments, and that the blocks or processes shown in the drawings are not necessarily required to practice the present disclosure and are, therefore, not intended to limit the scope of the present disclosure.

The following detailed description of embodiments of the invention is provided in conjunction with the accompanying drawings of fig. 1-13:

the rotor (structure) of the motor of the embodiment of the invention is an embedded rotor structure, and is characterized in that the relationship between the length of the extension part 12 and the thickness of the magnetic part 2 is set; and/or by providing the shape of the surface of the projection 12; and/or by providing recesses 13 on both sides of the extension 12 and by providing the shape of the recesses 13; the torque pulsation of the motor can be reduced, the vibration of the motor is reduced, and the noise of the motor is reduced. When the rotor of the motor is used as the rotor of the permanent magnet motor, the torque of the motor tooth groove 31 can be reduced, the running stability of the motor is improved, the low-speed running rotation speed fluctuation is reduced, and the stability of driving control is facilitated; the rotor (structure) of the embodiment of the invention simultaneously reduces the stray loss of the motor and can improve the motor efficiency to a certain extent.

Example one

As shown in fig. 1 to 6, the rotor of the motor according to the first embodiment of the present invention is an embedded rotor structure, and the relationship between the length of the protruding portion 12 and the thickness of the magnetic member 2 is set, so as to solve the problems of large torque ripple, large motor vibration and large noise of the existing motor; meanwhile, the problems of large torque and poor running stability of the motor tooth socket 31, and large rotating speed fluctuation especially when the motor runs at low speed can be solved; the motor torque ripple and the tooth space 31 torque are large, the stray loss of the motor can be reduced, and the motor efficiency is improved.

A rotor of a motor according to an embodiment of the present invention includes: the rotor comprises a rotor core 1, a plurality of extending parts 12 and a plurality of magnetic pieces 2, wherein the plurality of extending parts 12 are uniformly distributed on the circumference of the rotor core 1, each magnetic piece 2 of the plurality of magnetic pieces 2 is arranged between two adjacent extending parts 12, and the plurality of magnetic pieces 2 are alternately arranged along the circumference of the rotor core 1 according to N-S poles; in a cross section perpendicular to the central axis of the rotor core 1, the cross section of the top surface of the magnetic member 2 is a first circular arc, and the circular arc radius of the first circular arc is R1; in a cross section perpendicular to the central axis of the rotor core 1, the cross section of the inner surface of the magnetic member 2 is a second circular arc, and the circular arc radius of the second circular arc is R2; the thickness of the magnetic element 2 is R1-R2; in a section perpendicular to the central axis of the rotor core 1, the section of the top surface of the extension portion 12 of the rotor core 1 is a third circular arc, and the radius of the third circular arc is R3; the length of the extension 12 is h, h ═ R3-R2; wherein h is (0.3-0.7) × (R1-R2).

Wherein, magnetic part 2 is preferably the magnet steel, and the magnet steel can be formed by the whole die-casting of mould. The rotor of the motor is preferably used as the rotor of the permanent magnet motor, and the problem of overlarge torque of the motor tooth groove 31 can be solved. The rotor of motor, including rotor core 1, fixed support element such as magnet steel and bolt or rivet, rotor core 1 can be folded by the silicon steel sheet of 0.25 ~ 0.5mm thickness and press and form, has seted up through-hole 11 on rotor core 1, and through-hole 11 is used for placing fixed support element such as bolt or rivet, and fixed support element passes through-hole 11 and the cooperation of nut or is used for fastening rotor core 1 through the riveting. The even interval distribution of extension 12 is on rotor core 1, and the number of extension 12 is the same with the number of magnet steel, is used for placing the magnet steel between two adjacent extension 12, and the magnet steel is pasted or mechanical fixed's mode is according to N, S polarity alternate align to grid at rotor core 1's top surface through glue.

In the section of the rotor core 1 perpendicular to the central axis of the rotor core 1, the section of the top surface of the rotor core 1 is a fourth circular arc, and the radius of the fourth circular arc is R4; the first arc, the second arc, the third arc and the fourth arc are concentrically arranged, and R4 is R2. Preferably, the circular arc radius R3 meets the requirement that R2< R3 ≦ R1.

In order to reduce the torque ripple of the motor, the length h of the protruding portion 12 is (0.3 to 0.7) × (R1 to R2), that is, the arc radius R of the top surface of the protruding portion 12 satisfies 0.3 × R1+0.7 × R2 ≤ R ≤ 0.7 × R1+0.3 × R2, preferably, h is 0.5 × R (R1 to R2), that is, the arc radius R of the top surface of the protruding portion 12 is 0.5 × R1+0.5 × R2, and at this time, the length of the protruding portion 12 of the rotor core 1 is half of the thickness of the magnetic steel.

Each magnetic member 2 occupies a circumferential angle δ in the circumferential direction of rotor core 1, and each protruding portion 12 occupies a circumferential angle θ in the circumferential direction of rotor core 1, where δ and θ satisfy the relation δ + θ being 90 °. In the embodiment of the present invention, in order to reduce the motor torque ripple and fully utilize the reluctance torque generated by the rotor magnetic circuit, the angle size of the protruding portion 12 should satisfy the relation 1/8 × δ ≦ θ ≦ 1/2 × δ, and the angle size of the protruding portion 12 is preferably 1/4 × θ, where θ is 18 ° and δ is 72 °.

As shown in fig. 3, the motor using the rotor of the motor of the present invention includes a stator 3 and a rotor, wherein the stator 3 is further provided with a tooth slot 31, and the tooth slot 31 is used for winding a coil winding. Experiments and simulations show that the torque pulsation of the motor can be well reduced when the long part h of the extension part 12 is (0.3-0.7) × (R1-R2) and/or delta + theta is 90 DEG, 1/8 × delta is not more than theta is not more than 1/2 × delta. Wherein, satisfy simultaneously: when h is (0.3 to 0.7) × (R1 to R2) and δ + θ is 90 °, 1/8 × δ ≦ θ ≦ 1/2 × δ, the torque ripple is significantly reduced. As shown in fig. 5, a schematic diagram of comparing the torque ripple of the motor using the rotor of the motor with that of the motor using the rotor of the conventional motor is shown, and it can be seen that the torque ripple of the motor using the rotor of the motor according to the embodiment of the present invention is significantly reduced compared with the torque ripple of the conventional motor; by adopting the rotor of the motor, simulation shows that the torque pulsation of the motor is greatly reduced compared with the original traditional rotor, the peak value of the torque of the motor is reduced to 25.8mN m from the original 41.4mN m when the motor is in no load, and the technical effect is very obvious.

Example two

As shown in fig. 1-3, 6, and 7, the second embodiment illustrates an alternative embodiment in which the overall shape of the rotor (structure) is the same as the structure shown in fig. 1-3 of the first embodiment, except that the cross-sectional shape shown in fig. 6 is adopted.

The rotor of the motor of the second embodiment of the invention is of an embedded rotor structure, and the problems of large torque pulsation, large motor vibration and large noise of the existing motor are solved by arranging the surface shape of the extension part 12; meanwhile, the problems of large torque and poor running stability of the motor tooth socket 31, and large rotating speed fluctuation especially when the motor runs at low speed can be solved; the motor torque ripple and the tooth space 31 torque are large, the stray loss of the motor can be reduced, and the motor efficiency is improved.

As shown in fig. 6, the rotor of the motor according to the second embodiment includes: the rotor comprises a rotor core 1, a plurality of extending parts 12 and a plurality of magnetic pieces 2, wherein the plurality of extending parts 12 are distributed on the circumference of the rotor core 1, each magnetic piece 2 of the plurality of magnetic pieces 2 is arranged between two adjacent extending parts 12, and the plurality of magnetic pieces 2 are alternately arranged along the circumference of the rotor core 1 according to N-S poles; the top surface of the extension 12 of the rotor core 1 has a multi-segment circular arc shape in a cross section perpendicular to the central axis of the rotor core 1. Preferably, the plurality of protruding portions 12 are uniformly distributed on the circumferential direction of the rotor core 1.

The torque pulsation of the motor is further reduced by changing the shape of the top arc of the extension part 12, and the torque pulsation can be significantly reduced by changing the top arc of the extension part 12 into a wavy line. Wherein, preferred 12 top surface wave lines of extension are the multistage circular arcs that the radius is the same, can take 2 ~ 5 sections, preferred 3 sections circular arc wave lines.

The number of the multiple circular arcs is 2-5, and the radiuses of the multiple circular arcs are the same.

The center O' of the wavy line arc is on the bisector of the width of the protruding portion 12, the number n of the bisector is determined by the number m of the arc segments, and the relation n is 2 × m-1.

The radius of the circular arc of the wavy line is marked as Rs, and the relation of 0 & lt, Rs & lt, 3/4 & gth is satisfied, and preferably, Rs is 1/2 & gth.

In the motor using the rotor of the motor of the present invention, by setting the sectional shape of the top surface of the extension portion 12 to a multi-segment circular arc shape, it can be found through simulation that the torque ripple is greatly reduced. In the first embodiment of the present invention, the torque ripple can be further reduced by further forming the cross-sectional shape of the top surface of the extension portion 12 into a multi-step circular arc shape. As shown in fig. 7, the motor torque ripple is greatly reduced compared to the rotor according to the first embodiment, and the peak value of the motor torque at no load is reduced from 25.8mN × m to 14.9mN × m, which further reduces the torque ripple of the motor, and the technical effect is very significant.

EXAMPLE III

As shown in fig. 8-13, the third embodiment illustrates an alternative embodiment in which the overall shape of the rotor structure is the same as that shown in fig. 1-3 of the first embodiment, except that the projections 12 have the cross-sectional shape shown in fig. 8-9.

The rotor of the motor in the third embodiment of the invention is of an embedded rotor structure, and the problems of large torque pulsation, large vibration and large noise of the existing motor are solved by arranging the grooves 13 at the two sides of the extension part 12 and arranging the shapes of the grooves 13; meanwhile, the problems of large torque and poor running stability of the motor tooth socket 31, and large rotating speed fluctuation especially when the motor runs at low speed can be solved; the motor torque ripple and the tooth space 31 torque are large, the stray loss of the motor can be reduced, and the motor efficiency is improved.

As shown in fig. 8 to 10, the rotor of the motor according to the third embodiment includes: the rotor comprises a rotor core 1, a plurality of extending parts 12 and a plurality of magnetic pieces 2, wherein the plurality of extending parts 12 are distributed on the circumferential direction of the rotor core 1, each magnetic piece 2 of the plurality of magnetic pieces 2 is arranged between two adjacent extending parts 12, and the plurality of magnetic pieces 2 are alternately arranged along the circumferential direction of the rotor core 1 according to N-S poles; grooves 13 are formed on two sides of part or all of the plurality of extending parts 12. Preferably, the grooves 13 are used to reduce torque ripple of the motor. Preferably, the plurality of protruding portions 12 are evenly distributed in the circumferential direction of the rotor core 1. The cross section of the groove 13 in the cross section perpendicular to the central axis of the rotor core 1 is a single semicircle or an equilateral triangle or a double semicircle.

The two sides of the extension part 12 are in the section vertical to the central axis of the rotor core 1, and the section is a straight line; the cross section of the groove 13 is in the shape of a single semicircle, and the center of the single semicircle is located at the middle point of the straight line of the cross sections of the two sides of the extension part 12.

The length of the protrusion 12 protruding from the rotor core 1 is denoted as h, and the radius of the single semicircle is r1, wherein 1/8 × h is not less than r1 is not more than 3/8 × h, and wherein r1 is 1/2 × h.

As shown in fig. 8 and 11, when the semicircular grooves 13 are formed on both sides of the protruding portion 12 of the rotor core 1, the motor torque ripple simulation value and the conventional motor torque ripple simulation value have a value, for example, as shown in fig. 11, in which the motor torque ripple is reduced from 65.87% to 36.05%, and the torque ripple improvement effect is significant.

As shown in fig. 9 and 12, the two sides of the protruding portion 12 are in a cross section perpendicular to the central axis of the rotor core 1, and the cross section is a straight line; the cross section of the groove 13 is triangular, and the middle point of the bottom edge of the triangle is positioned on the middle point of the straight lines of the cross sections at the two sides of the extension part 12. The triangle is an equilateral triangle, the side length of the equilateral triangle is r2, wherein, r2 is not less than 1/8 h and not more than 3/8 h.

As shown in fig. 12, when the protruding portion 12 of the rotor core 1 is formed in an equilateral triangle, the motor torque ripple simulation value and the original motor torque ripple simulation value are compared, for example, as shown in fig. 12, the motor torque ripple is reduced from 65.87% to 38.79%, and the torque ripple improvement effect is slightly worse than that of the semicircular groove 13.

As shown in fig. 10 and 13, the two sides of the protruding portion 12 are in a cross section perpendicular to the central axis of the rotor core 1, and the cross section is a straight line; the cross section of the groove 13 is in a double semicircle shape, and the centers of the double semicircle are respectively located at the 1/4 point and the 3/4 point of the cross section straight line on both sides of the extension part 12. The length of the protruding portion 12 protruding from the rotor core 1 is denoted by h, the radius of the double semicircle is the same, and the radius is denoted by r3, where r3 is 1/4 × h.

As shown in fig. 13, when the protruding portion 12 of the rotor core 1 is formed with the double semicircular grooves 13, the motor torque ripple simulation value and the original motor torque ripple simulation value have a value of 42.68% reduced from the original 65.87%, which is shown in fig. 13, and the torque ripple improvement effect is good.

In the first, second and third examples of the embodiment of the present invention, the length of the protruding portion 12, the shape of the top surface of the protruding portion 12 and the two sides of the protruding portion 12 are respectively provided with the grooves 13, so as to reduce the torque pulsation of the motor. Obviously, any combination of the schemes of the first embodiment, the second embodiment and the third embodiment is within the protection scope of the invention; for example, on the basis of the first embodiment, the surface shape limitation of the second embodiment and/or the limitation of the two sides of the extension part 12 provided with the grooves 13 of the third embodiment can be further adopted; on the basis of the second embodiment, the limitation that the length of the protruding part 12 in the first embodiment and/or the grooves 13 are formed in the two sides of the protruding part 12 in the third embodiment can be further adopted; the length of the protruding portion 12 and/or the surface shape defined in the second embodiment can be further defined in the first embodiment on the basis of the third embodiment. Through the further limitation, the technical scheme of the embodiment of the invention can be further optimized, and the torque pulsation of the motor can be better reduced.

Has the advantages that:

the rotor of the motor of the embodiment of the invention is of an embedded rotor structure, and is characterized in that the relationship between the length of the extending part and the thickness of the magnetic part is set; and/or by providing the shape of the surface of the projection; and/or, by arranging grooves on both sides of the protruding part and by arranging the shape of the grooves; the torque pulsation of the motor is reduced, so that the vibration of the motor is reduced, and the noise of the motor is reduced; the rotor of the embodiment of the invention simultaneously reduces the cogging torque of the motor, improves the running stability of the motor, reduces the low-speed running rotation speed fluctuation and is beneficial to controlling the driving stability; the rotor structure of the embodiment of the invention simultaneously reduces the stray loss of the motor and can improve the efficiency of the 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

1. A rotor of an electric machine comprising: rotor core (1), a plurality of magnetism spare (2), its characterized in that: a plurality of extending parts (12) are formed on the circumferential direction of the rotor core (1), and the plurality of extending parts (12) radially protrude from the circumferential surface of the rotor core (1); the magnetic piece (2) is arranged between every two adjacent protruding parts (12) of the protruding parts (12), and the magnetic pieces (2) are alternately arranged along the circumferential direction of the rotor core (1) according to N-S poles; part or all of the extension parts (12) are in a section perpendicular to the central axis of the rotor core (1), and the section of the top surface of the extension parts is a multi-segment line;

in a section perpendicular to the central axis of the rotor core (1), the sections of the top surface and the inner surface of the magnetic part (2) are respectively a first circular arc and a second circular arc, and the first circular arc and the second circular arc are concentrically arranged;

the arc radius of the first arc is R1, the arc radius of the second arc is R2, the thickness of the magnetic element (2) is R1-R2, and the length of the extension part (12) is h = (0.3-0.7) × (R1-R2);

in a section perpendicular to the central axis of the rotor core (1), the sections of two side edges of the extension part (12) are straight lines;

the multi-line segment is formed into a wave shape;

each section of the multi-section line is arc-shaped;

the number of the segments of the multi-segment line segment is 2 or 3 or 4 or 5, the radiuses of the circular arcs of the multi-segment circular arc are the same, and the radiuses are marked as Rs.

2. The rotor of an electric machine of claim 1, wherein: the length of the plurality of the protruding parts (12) protruding out of the rotor core (1) in the radial direction is recorded as h, wherein Rs is more than or equal to 0 and less than or equal to 3/4.

3. The rotor of an electric machine of claim 2, wherein: the circle center O' of each arc of the plurality of arc-shaped sections is on an equal dividing line of the width of the extension part (12), the number n of the equal dividing lines is determined by the number m of the arc-shaped sections of the plurality of arc-shaped sections, and the relation n =2 × m-1 is satisfied.

4. The rotor of an electric machine of claim 1, wherein: the plurality of protruding portions (12) are uniformly distributed in the circumferential direction of the rotor core (1).

5. The rotor of an electric machine of claim 1, wherein: grooves (13) are formed in two sides of part or all of the extending parts (12).

6. The rotor of an electric machine of claim 5, wherein: the groove (13) is in a section perpendicular to the central axis of the rotor core (1), and the section of the groove is in the shape of a single semicircle or an equilateral triangle or a double semicircle.

7. An electric machine characterized by: the electrical machine comprising a rotor of an electrical machine according to any of claims 1-6.