CN219802002U - Rotor structure and motor - Google Patents

Abstract

The utility model provides a rotor structure and a motor. The rotor structure comprises a rotor core (1) and a plurality of permanent magnets (2) which are attached to the periphery of the rotor core (1), wherein the permanent magnets (2) are uniformly distributed along the circumference of the rotor core (1), and at least two grooves (3) which are symmetrical with respect to the magnetic pole center line of the permanent magnets (2) are formed in the outer surface of the permanent magnets (2). According to the rotor structure, the cogging torque and the eddy current loss of the motor can be effectively reduced, and the motor efficiency is improved.

Description

Rotor structure and motor

Technical Field

The utility model relates to the technical field of motors, in particular to a rotor structure and a motor.

Background

The rotor of the surface-mounted permanent magnet synchronous motor is provided with magnetic flux by two permanent magnets together at each pole, and compared with other rotor motors, the power density of the surface-mounted permanent magnet synchronous motor can be higher. However, due to the characteristics of a tooth space physical structure and the wide application of a neodymium iron boron permanent magnet material, the phenomenon of tooth space torque and permanent magnet eddy current loss occurs in the running process of the motor, so that the torque of the motor fluctuates, the temperature of the permanent magnet rises, the distribution of the air gap density (air gap magnetic field) of the motor is further affected, and finally vibration, noise and motor efficiency decline are caused. Therefore, how to solve the problem of high cogging torque and high permanent magnet eddy current loss of the high-power-density permanent magnet synchronous motor is a problem which a motor developer aims to solve.

Disclosure of Invention

The utility model mainly aims to provide a rotor structure and a motor, which can effectively reduce cogging torque and eddy current loss of the motor and improve motor efficiency.

In order to achieve the above object, according to an aspect of the present utility model, there is provided a rotor structure including a rotor core and permanent magnets surface-mounted on an outer periphery of the rotor core, the permanent magnets being a plurality of permanent magnets uniformly distributed along a circumferential direction of the rotor core, an outer surface of the permanent magnets being provided with at least two grooves symmetrical with respect to a magnetic pole center line of the permanent magnets.

Further, the radial thickness of the permanent magnet is h1, and the radial height of the groove is h2, wherein 0 < h2/h1 is less than or equal to 0.7.

Further, the number of the grooves is two, and the opening width of the grooves is b2, and b2 is more than 0 and less than or equal to 1mm.

Further, the opening width of the groove is b2, and b2 is more than 0 and less than or equal to 0.2mm.

Further, the number of grooves is two, the distance between the two grooves on the same permanent magnet and the central line of the magnetic pole of the permanent magnet is b1, the circumferential width of the permanent magnet is 2a, and 0.25 is less than or equal to 2b1/2 a=b1/a is less than or equal to 0.5.

Further, b1 is more than or equal to 2mm and less than or equal to 4mm, and 15mm is more than or equal to 2a is more than or equal to 17mm.

Further, the number of the grooves is two, the opening width of the grooves is b2, the distance between the two grooves on the same permanent magnet and the central line of the magnetic pole of the permanent magnet is b1, and the relationship between b1 and b2 satisfies that b2/b1 is more than or equal to 0.1 and less than or equal to 1.5.

Further, in a cross section perpendicular to the central axis of the rotor core, the shape of the groove is rectangular, U-shaped, arc-shaped, or parallelogram.

Further, in a cross section perpendicular to the central axis of the rotor core, the shape of the groove is a parallelogram, the parallelogram comprises side edges located on two sides along the circumferential direction, a connecting line between the end point of the outer end of one side edge and the circle center of the rotor core is a first connecting line, an included angle formed by the side edge and the first connecting line is theta 3, and theta 3 satisfies 15 degrees or more and less than or equal to 75 degrees or less.

Further, the grooves extend in the axial direction of the rotor core.

Further, the grooves penetrate through two ends of the rotor core along the axial direction; or the groove penetrates through one end of the rotor core along the axial direction; or, the grooves are spaced from both end surfaces of the rotor core by a predetermined distance.

According to another aspect of the present utility model, there is provided an electric machine comprising a rotor structure as described above.

Further, the motor also comprises a stator structure, the rotor structure is sleeved in the stator structure, the stator structure comprises stator windings, and the stator windings are concentrated windings.

By applying the technical scheme of the utility model, the rotor structure comprises a rotor core and a plurality of permanent magnets which are surface-mounted on the periphery of the rotor core, wherein the plurality of permanent magnets are uniformly distributed along the circumferential direction of the rotor core, and at least two grooves which are symmetrical relative to the magnetic pole center line of the permanent magnets are arranged on the outer surface of the permanent magnets. By arranging at least two grooves symmetrical to the magnetic pole center line of the permanent magnet on the rotor structure, the magnetic circuit on the surface of the permanent magnet can be optimally adjusted by utilizing the grooves, the magnetic field distribution condition between the stator and the rotor is improved, the cogging torque is reduced, the skin effect on the surface of the permanent magnet is reduced, and the eddy current density on the surface of the permanent magnet is effectively reduced, so that the motor efficiency is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the utility model. In the drawings:

fig. 1 shows a schematic structural view of an electric motor according to an embodiment of the present utility model;

FIG. 2 shows a structural dimension of a rotor structure of an embodiment of the present utility model;

FIG. 3 shows a structural dimension of a rotor structure of an embodiment of the present utility model;

fig. 4 shows a schematic structural view of a motor according to an embodiment of the present utility model;

FIG. 5 shows a partial enlarged view at A of FIG. 4;

FIG. 6 shows an equivalent impedance diagram of an ungrooved permanent magnet of the related art;

FIG. 7 shows an equivalent impedance diagram of a slotted permanent magnet of an embodiment of the present utility model;

FIG. 8 shows the eddy current profile of an ungrooved permanent magnet of the related art;

FIG. 9 shows an eddy current profile of a slotted permanent magnet in accordance with an embodiment of the present utility model;

FIG. 10 shows a cogging torque graph of an ungrooved permanent magnet of the related art;

FIG. 11 shows b1, b2 graphs of cogging torque of a rotor structure of an embodiment of the utility model; and

fig. 12 shows an h1 graph of the cogging torque of the rotor structure of the embodiment of the present utility model.

Wherein the above figures include the following reference numerals:

1. a rotor core; 2. a permanent magnet; 3. a groove; 4. a stator structure.

Detailed Description

It should be noted that, without conflict, the embodiments of the present utility model and features of the embodiments may be combined with each other. The utility model will be described in detail below with reference to the drawings in connection with embodiments.

Referring to fig. 1 to 5 in combination, according to an embodiment of the present utility model, a rotor structure includes a rotor core 1 and permanent magnets 2 surface-mounted on an outer periphery of the rotor core 1, the permanent magnets 2 being plural, the plural permanent magnets 2 being uniformly distributed in a circumferential direction of the rotor core 1, an outer surface of the permanent magnets 2 being provided with at least two grooves 3 symmetrical with respect to a magnetic pole center line of the permanent magnets 2.

By arranging at least two grooves 3 symmetrical to the magnetic pole center line of the permanent magnet 2 on the rotor structure, the magnetic circuits on the surface of the permanent magnet 2 can be optimally adjusted by utilizing the grooves 3, the magnetic field distribution condition between the stator and the rotor is improved, the cogging torque is reduced, the skin effect on the surface of the permanent magnet 2 is reduced, the eddy current density on the surface of the permanent magnet 2 is effectively reduced, the temperature rise of the permanent magnet is reduced, and the motor efficiency is improved.

In one embodiment, the outer circumference of the rotor core 1 is in a full circle structure, and the permanent magnets 2 are fixedly adhered to the surface of the rotor core 1 through glue and then magnetized. In the present embodiment, the permanent magnet 2 is located entirely outside the rotor core 1.

In one embodiment, a mounting groove is formed in the peripheral wall of the permanent magnet 2, and the permanent magnet is embedded in the mounting groove and then bonded and fixed by glue. In this embodiment, the permanent magnet 2 may be completely embedded in the installation groove or may be partially embedded in the installation groove.

In one embodiment, the permanent magnets 2 are magnetized tangentially, and the polarities of the mutually facing surfaces of two adjacent permanent magnets 2 are the same, so that magnetomotive force of the poles is provided together, the power density of the motor is greatly improved, and the motor can be miniaturized.

In one embodiment, the number of permanent magnets 2 is 10.

In one embodiment, the permanent magnet 2 is tile-shaped.

In one embodiment, the radial thickness of the permanent magnet 2 is h1, and the radial height of the groove 3 is h2, wherein 0 < h2/h1 is less than or equal to 0.7.

In this embodiment, by limiting the proportional relationship between the radial thickness h1 of the permanent magnet 2 and the radial height h2 of the groove 3, the value of h2 can be associated with h1, so that h2 can be limited by h1, the radial height of the groove 3 can be adaptively adjusted according to the change of the radial thickness of the permanent magnet 2, a better matching relationship can be obtained, the obtained permanent magnet 2 can effectively destroy the skin effect of the surface of the permanent magnet, the eddy current of the surface of the permanent magnet 2 is reduced, the temperature rise of the permanent magnet 2 is reduced, and the working performance of the permanent magnet 2 is improved.

h2 represents the grooving depth of the permanent magnet 2, so the value of h2 should not be too large, and the mechanical strength of the permanent magnet 2 needs to be ensured. To achieve this, the grooving depth h2 of the permanent magnet 2 should not exceed 70% of the radial thickness h1 of the permanent magnet 2, i.e. 0 < h2/h 1.ltoreq.0.7.

In one embodiment, h2/h1 is more than or equal to 0.1 and less than or equal to 0.7, so that the groove 3 on the permanent magnet 2 has enough depth, the surface structure of the permanent magnet 2 can be optimized, the skin effect on the surface of the permanent magnet 2 can be effectively destroyed, the eddy current loss is reduced, the mechanical strength of the permanent magnet 2 can be greatly reduced due to overlarge depth of the groove 3 on the permanent magnet 2, and the permanent magnet 2 can be ensured to stably and reliably operate.

In one embodiment, the number of the grooves 3 is two, and the opening width of the grooves 3 is b2, and 0 < b2 is less than or equal to 1mm.

By limiting the opening width of the groove 3 so as not to exceed 1mm, the reduction of the mechanical strength and motor performance of the permanent magnet due to the excessive grooving width can be avoided.

In one embodiment, the opening width of the groove 3 is b2, and b2 is more than 0 and less than or equal to 0.2mm, so that the cogging torque of the motor can be more effectively reduced on the basis of avoiding the reduction of the mechanical strength and the motor performance of the permanent magnet due to the overlarge slotting width.

In one embodiment, the number of grooves 3 is two, the distance between two grooves 3 on the same permanent magnet 2 and the magnetic pole center line of the permanent magnet 2 is b1, and the circumferential width of the permanent magnet 2 is 2a, and 0.25 is less than or equal to 2b1/2 a=b1/a is less than or equal to 0.5.

As shown in fig. 11 and 12 in combination, when b1=0.5, 1, 3, and 4mm, the cogging torque gradually increases with an increase in b2, and when b1=2 and 5.5mm, the cogging torque gradually decreases with an increase in b 2. Therefore, the trough range of the cogging torque can be determined according to the characteristics, and the relationship between the interval 2b1 between the two grooves 3 and the circumferential width 2a of the permanent magnet 2 can be further determined, so that the cogging torque generated by the motor can be controlled within a preferable range. It is found that when the relation between b1 and a satisfies 0.25.ltoreq.b1/a.ltoreq.0.5, the slotting of the permanent magnet 2 can reduce the cogging torque of the motor well.

As can be seen from a comparison of the cogging torque of the permanent magnet ungrooved motor in the related art and the cogging torque of the permanent magnet slotted motor of the embodiment of the present utility model, when b2=0.2 mm, b1=0.5, 3, 3.5, 4, and 6mm, the cogging torque of the permanent magnet slotted motor is smaller than that of the ungrooved motor.

When two points b1=0.5, b2=0.2 mm and b1=0.35, b2=0.4 mm are selected which are good in fig. 11, the values of h1 are changed by using the parameters of the two points, and it can be seen from fig. 12 that the cogging torque gradually decreases with the increase of h2, but the decreasing trend becomes very slow after h2 is 0.9-1 mm. Therefore, when the h2/h1 is more than or equal to 0.4 and less than or equal to 0.5, the method is an optimal solution for reducing the cogging torque.

As can be seen from fig. 11 and 12, by comparing the influences of the b1, b2 and h2 parameters on the cogging torque, it is obtained that the influences of the b1, b2 parameters on the cogging torque of the motor are larger, and the influences of the slotting depth h2 on the cogging torque of the motor are smaller after reaching a certain value, so that when the permanent magnet is slotting, the slotting depth h2 can be preset according to the size of h1 first, and then the design of the parameters b1 and b2, that is, the distance between the two grooves 3 and the opening width of the grooves 3 is focused.

In one embodiment, 2 mm.ltoreq.b1.ltoreq.4mm, 15 mm.ltoreq.2a.ltoreq.17mm. The interval between two recesses 3 is influenced by the circumferential width of the permanent magnet 2, the matching relationship between the two has a great influence on the cogging torque of the motor, and the recesses on the surface of the permanent magnet 2 can form a good structural design by reasonably limiting the numerical matching relationship between the two, so that the cogging torque of the motor can be controlled in a lower range, the working performance of the motor is improved, and the temperature rise of the permanent magnet is reduced.

In one embodiment, 2.5 mm.ltoreq.b1.ltoreq.3.5 mm, 2a=16 mm.

In one embodiment, the number of the grooves 3 is two, the opening width of the grooves 3 is b2, the distance between the two grooves 3 on the same permanent magnet 2 and the central line of the magnetic pole of the permanent magnet 2 is b1, the relationship between b1 and b2 satisfies that b2/b1 is more than or equal to 0.1 and less than or equal to 1.5, and the cogging torque of the motor can be smaller.

In one embodiment, b2/b1 is more than or equal to 0.1 and less than or equal to 0.3, and the structural design of the grooves 3 is better in the value range, so that the matching relation between the opening width of the grooves 3 and the distance between the two grooves 3 is better, and the cogging torque of the motor can be reduced more effectively.

In one embodiment, the width of the recess 3 is greatest at the opening.

In one embodiment, the parameters of the motor are as follows:

rotor outer diameter = 63mm;

air gap length q=1 mm;

stator outer diameter = 124mm;

permanent magnet thickness h1=2 mm.

Equation 1 is a calculation equation of motor cogging torque, and l in equation 1 represents motor axial length.

As shown in fig. 10, by simulating the cogging torque of the permanent magnet ungrooved motor in the related art, it is possible to calculate cogging torque=58.0315mn.m.

Wherein the value of h2 is less than or equal to 1.4mm, and b2 is less than or equal to 1mm.

In one embodiment, the angle between two grooves 3 on the same permanent magnet 2 is θ1, 6+.ltoreq.θ1+.ltoreq.15 °. θ1 can define an angle between the two grooves 3, and the distance between the two grooves 3 can be determined in accordance with the diameter of the rotor core 1.

In one embodiment, the angle between the radially outer end points of the both side edges of the groove 3 and the center line of the rotor core 1 is θ2,0.5 Σ1 Σ2°.

The shape of the recess 3 may be various, and in one embodiment, the recess 3 is rectangular, U-shaped, arc-shaped, or parallelogram in a cross section perpendicular to the central axis of the rotor core 1.

In one embodiment, in a cross section perpendicular to the central axis of the rotor core 1, the shape of the recess 3 is a parallelogram including side edges located on both sides in the circumferential direction, a line between the outer end point of one of the side edges and the center of the rotor core is a first line, and an included angle formed by the side edge and the first line is θ3, wherein θ3 satisfies 15+.θ3+.75 °.

In this embodiment, the shape of the groove 3 is a parallelogram, so that the groove 3 forms an inclined structure, which can reduce eddy current loss of the permanent magnet 2 more effectively and improve working performance of the permanent magnet.

In one embodiment, the grooves 3 extend in the axial direction of the rotor core 1.

In one embodiment, the grooves 3 penetrate through two ends of the rotor core 1 along the axial direction, the structure is simple to process, the surface structure of the permanent magnet 2 can be effectively blocked, and the skin effect of the surface of the permanent magnet 2 can be effectively destroyed.

In one embodiment, the recess 3 extends axially through one end of the rotor core 1.

In one embodiment, the grooves 3 are spaced apart from both end surfaces of the rotor core 1 by a predetermined distance.

The axial extension length of the groove 3 can be designed and arranged according to the requirement, so that the structural design is more flexible, and the required structure can be obtained more conveniently.

The simplified model of the equivalent impedance of the permanent magnet 2 is shown in fig. 6 and 7, wherein fig. 6 is a model diagram of the equivalent impedance of an ungrooved permanent magnet in the related art, and fig. 7 is a model diagram of the equivalent impedance of a grooved permanent magnet in the embodiment of the utility model, wherein the width of the permanent magnet is 2a, and the axial length of the permanent magnet is 2b. The permanent magnet blocking effect can be understood as an increase in the equivalent resistance of the permanent magnet.

After the two grooves 3 are formed in the permanent magnet 2, the surface of the permanent magnet 2 is divided into three pieces, and the number of the equivalent resistors Rb is 2. When the permanent magnet is divided into N segments, there will be N more Rb.

According to the skin effect of the eddy current, the eddy current is distributed on the surface of the permanent magnet; the eddy current distribution before and after slotting of the permanent magnet is shown in fig. 8 and 9, wherein fig. 8 is an eddy current distribution diagram of an ungrooved permanent magnet in the related art, and fig. 9 is an eddy current distribution diagram of a slotted permanent magnet in an embodiment of the present utility model, and as can be seen from comparison of fig. 8 and 9, the eddy current density of the surface of the permanent magnet 2 can be effectively reduced after slotting of the permanent magnet.

The eddy current loss of the permanent magnet before and after slotting can be calculated through a formula 2, wherein N represents the number of permanent magnet segments; the motor eddy current loss W with ungrooved permanent magnets is calculated ungrooved=45w, motor W with slotted permanent magnets is slotted=18w.

The difference value between the eddy current loss of the motor adopting the slotted permanent magnet and the eddy current loss of the motor adopting the ungrooved permanent magnet is 45-18=27w, the eddy current loss reduction ratio is 27W/45 w=60%, namely the eddy current loss of the motor adopting the rotor structure of the embodiment of the utility model is reduced by 60% compared with the motor in the related art, the eddy current loss is greatly reduced, thus the temperature rise of the permanent magnet is effectively controlled, and the motor performance is effectively improved.

According to the calculation result, the permanent magnet slotting can well reduce the eddy current loss of the permanent magnet.

By combining the analysis, when the fixed air gap length Q=1mm, the rotor outer diameter=63 mm and the permanent magnet thickness=2mm, the cogging torque of the motor can be well reduced by arranging the grooves 3 at symmetrical positions on two sides of the center line of the permanent magnet, and changing the groove width b2, the two groove distances 2b1 and the groove depth h1 of the grooves 3; through carrying out the circumference fluting to the permanent magnet, can reduce the eddy current loss of permanent magnet effectively, and then improve the permanent magnet condition of generating heat.

According to an embodiment of the utility model, the motor comprises a rotor structure, which is the rotor structure described above.

In one embodiment, the motor further comprises a stator structure 4, the rotor structure being sleeved inside the stator structure 4, the stator structure 4 comprising stator windings, the stator windings being concentrated windings.

An air gap is formed between the stator core of the stator structure 4 and the permanent magnet 2 of the rotor structure, and the length of the air gap is Q. The stator core and the rotor core are formed by laminating electro-permanent magnet plates, most of the rotor structure is a main magnetic circuit, and the stator core provide magnetic circuits for magnetomotive force together.

In one embodiment, the motor is a permanent magnet synchronous motor.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present utility model. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present utility model and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the utility model described herein may be implemented in sequences other than those illustrated or otherwise described herein.

The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, but various modifications and variations can be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

Claims (13)

1. The rotor structure is characterized by comprising a rotor core (1) and permanent magnets (2) which are surface-mounted on the periphery of the rotor core (1), wherein the number of the permanent magnets (2) is multiple, the plurality of the permanent magnets (2) are uniformly distributed along the circumferential direction of the rotor core (1), and at least two grooves (3) which are symmetrical with respect to the magnetic pole center line of the permanent magnets (2) are formed in the outer surface of the permanent magnets (2).

2. Rotor structure according to claim 1, characterized in that the radial thickness of the permanent magnets (2) is h1 and the radial height of the grooves (3) is h2, wherein 0 < h2/h1 is less than or equal to 0.7.

3. Rotor structure according to claim 1, characterized in that the number of grooves (3) is two, the opening width of the grooves (3) being b2,0 < b2 < 1mm.

4. A rotor structure according to claim 3, characterized in that the opening width of the groove (3) is b2,0 < b2 < 0.2mm.

5. The rotor structure according to claim 1, characterized in that the number of the grooves (3) is two, the distance between the two grooves (3) on the same permanent magnet (2) and the magnetic pole center line of the permanent magnet (2) is b1, and the circumferential width of the permanent magnet (2) is 2a, 0.1-2 b1/2a = b 1/a-0.7.

6. The rotor structure of claim 5, wherein 1 mm.ltoreq.b1.ltoreq.6mm, 15 mm.ltoreq.2a.ltoreq.17 mm.

7. The rotor structure according to claim 1, wherein the number of the grooves (3) is two, the opening width of the grooves (3) is b2, the distance between the two grooves (3) on the same permanent magnet (2) and the magnetic pole center line of the permanent magnet (2) is b1, and the relationship between b1 and b2 satisfies 0.1.ltoreq.b2/b 1.ltoreq.1.5.

8. The rotor structure according to any one of claims 1 to 7, characterized in that the shape of the recess (3) is rectangular, U-shaped, arcuate or parallelogram in a cross section perpendicular to the central axis of the rotor core (1).

9. A rotor structure according to any one of claims 1-7, characterized in that the recess (3) has a parallelogram shape in a cross section perpendicular to the central axis of the rotor core (1), the parallelogram shape comprising side edges located circumferentially on both sides, wherein a line between the outer end points of one of the side edges and the centre of the rotor core is a first line, and the side edges and the first line form an angle θ3, wherein θ3 satisfies 15 ° - θ3 +.75 °.

10. A rotor structure according to any one of claims 1-7, characterized in that the grooves (3) extend in the axial direction of the rotor core (1).

11. The rotor structure according to claim 10, characterized in that the grooves (3) axially penetrate through both ends of the rotor core (1); or the groove (3) penetrates through one end of the rotor core (1) along the axial direction; or, the grooves (3) are spaced from both end faces of the rotor core (1) by a preset distance.

12. An electric machine comprising a rotor structure, characterized in that the rotor structure is a rotor structure according to any one of claims 1 to 11.

13. The electric machine according to claim 12, characterized in that the electric machine further comprises a stator structure (4), the rotor structure being nested within the stator structure (4), the stator structure (4) comprising stator windings, which are concentrated windings.