Rotor assembly and electric machine having the same

Abstract

The application provides a rotor assembly and a motor with the same, wherein the rotor assembly comprises a rotor core and a plurality of permanent magnets which are surface-mounted on the outer circumferential surface of the rotor core and are distributed at intervals, the permanent magnet comprises a first transition portion, a second transition portion and a main body portion, the first transition portion and the second transition portion are respectively located at two sides of the main body portion, the first transition portion and the second transition portion are diagonally distributed relative to the main body portion, the maximum width of the first transition portion and the second transition portion is smaller than the minimum width of the main body portion, and the height of the first transition portion and the second transition portion is smaller than the height of the main body portion. According to the application, since the permanent magnet comprises the main body portion and the first transition portion and the second transition portion which are located at two opposite corners of the main body portion, the magnetic field intensity gradually decreases in the direction from the main body portion to the interval between two adjacent permanent magnets, instead of suddenly decreasing, so that the no-load cogging torque can be reduced and the load torque fluctuation can be reduced.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, specifically relating to a rotor assembly and a motor having the same. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) offer excellent energy efficiency and are widely used in industrial applications. Torque density is a crucial performance indicator for PMSMs, while cogging torque significantly impacts their position control accuracy, noise, and vibration performance. Therefore, improving torque density and optimizing cogging torque are essential for PMSMs and servo control systems. Currently, the arrangement of surface-mounted permanent magnets on the rotor core of traditional surface-mounted PMSMs is as follows: Figure 10 As shown, since each permanent magnet is a regular arc shape, that is, the projections of the two ends of each permanent magnet in the axial direction coincide with each other, and there is a constant width of gap between two adjacent permanent magnets (the gap is filled with air), the magnetic field strength at the gap is suddenly and significantly weaker than the magnetic field strength at the center of the magnetic pole. This makes the movement of the rotor's magnetic pole center from one stator tooth center to another stator tooth center a jump motion, resulting in large cogging torque pulsation and large load torque fluctuation of the motor. Summary of the Invention

[0003] Therefore, the present invention provides a rotor assembly that can solve the technical problem of large load torque fluctuation in existing surface-mounted permanent magnet synchronous motors.

[0004] To address the aforementioned problems, the present invention provides a rotor assembly comprising a rotor core and at least two permanent magnets. Each permanent magnet is surface-mounted on the outer circumferential surface of the rotor core and is distributed at intervals along the circumferential direction of the rotor core. Each permanent magnet includes a first transition portion, a second transition portion, and a main body portion. Along the circumferential direction of the rotor core, the first and second transition portions are respectively located on both sides of the main body portion, and the first and second transition portions are diagonally distributed relative to the main body portion. The maximum width of both the first and second transition portions is less than the minimum width of the main body portion. Along the axial direction of the rotor core, the height of both the first and second transition portions is less than the height of the main body portion.

[0005] In some embodiments, the main body has a center point, and the first transition portion and the second transition portion are centrally symmetrical about the center point.

[0006] In some embodiments, the height of the main body is H1, the height of the first transition portion is h1, and the height of the second transition portion is h2, where H1 ≤ h1 + h2 < 2 * H1.

[0007] In some embodiments, the first transition portion has a first side plane facing away from the main portion, the second transition portion has a second side plane facing away from the main portion, the main portion has a fifth side plane on the side of the first transition portion and a sixth side plane on the side of the second transition portion, an included angle between the first side plane and the fifth side plane is a1, an included angle between the second side plane and the sixth side plane is a2, and an included angle between the fifth side plane and the sixth side plane is A, 0 < (a1 + a2) / A < 1.

[0008] In some embodiments, the permanent magnet further comprises a third transition portion and a fourth transition portion; along a circumferential direction of the rotor core, the third transition portion is on a side of the first transition portion facing away from the main portion, and a maximum width of the third transition portion is less than a minimum width of the first transition portion, and the fourth transition portion is on a side of the second transition portion facing away from the main portion, and a maximum width of the fourth transition portion is less than a minimum width of the second transition portion; along an axial direction of the rotor core, a height of the third transition portion is less than a height of the first transition portion, and a height of the fourth transition portion is less than a height of the second transition portion.

[0009] In some embodiments, the main portion has a center point, and the third transition portion and the fourth transition portion are centrosymmetric about the center point.

[0010] In some embodiments, a height of the main portion is H1, a height of the third transition portion is h3, and a height of the fourth transition portion is h4, 2 / 3 * H1 ≤ h3 + h4 < 4 / 3 * H1.

[0011] In some embodiments, the first transition portion has a first side plane facing away from the main portion, the second transition portion has a second side plane facing away from the main portion, the third transition portion has a third side plane facing away from the first transition portion, the fourth transition portion has a fourth side plane facing away from the second transition portion, the main portion has a fifth side plane on the side of the first transition portion and a sixth side plane on the side of the second transition portion, an included angle between the first side plane and the third side plane is a3, an included angle between the second side plane and the fourth side plane is a4, and an included angle between the fifth side plane and the sixth side plane is A, 0 < (a3 + a4) / A < 0.5.

[0012] In some embodiments, a plurality of first protrusions are formed on the outer circumferential surface of the rotor core, each of the first protrusions is in abutment with each of the first transition portions along the axial direction of the rotor core, and each of the first protrusions is in contact with the main body portion; and / or, a plurality of second protrusions are formed on the outer circumferential surface of the rotor core, each of the second protrusions is in abutment with each of the second transition portions along the axial direction of the rotor core, and each of the second protrusions is in contact with the main body portion.

[0013] In some embodiments, along the axial direction of the rotor core, the height of the rotor core is H2, the height of the main body portion is H1, and H1≤1.3*H2.

[0014] The application also provides an electric machine comprising the aforementioned rotor assembly.

[0015] The application provides a rotor assembly and an electric machine comprising the same, which have the following advantages:

[0016] Since each level of the permanent magnets comprises the main body portion and the first and second transition portions located at two opposite corners of the main body portion, the first and second transition portions are also diagonally distributed between adjacent permanent magnets. Since the height and the maximum width of the first and second transition portions are less than the height and the minimum width of the main body portion, respectively, the magnetic field strength gradually decreases in the direction from the main body portion to the space between the adjacent permanent magnets, instead of suddenly decreasing, so that the movement of the center of the magnetic pole of the rotor from one stator tooth center to another stator tooth center is no longer a jump movement, but a relatively gentle movement, thereby reducing the no-load cogging torque of the electric machine and reducing the load torque fluctuation. Meanwhile, the diagonal distribution of the first and second transition portions between the adjacent permanent magnets makes the coverage range of the transition magnetic field wider and the buffering effect better. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only exemplary, and for those skilled in the art, other drawings can be derived from the provided drawings without creative labor.

[0018] Figure 1 Structure diagram of the rotor assembly of the first embodiment of the application;

[0019] Figure 2 Structure diagram of the permanent magnet of the rotor assembly of the first embodiment of the application;

[0020] Figure 3Fig. 3 is a schematic view of the permanent magnet of the rotor assembly of the first embodiment of the present application from another perspective;

[0021] Figure 4 Fig. 4 is a schematic view of the structure of the rotor core of the rotor assembly of the first embodiment of the present application;

[0022] Figure 5 Fig. 5 is a schematic view of the structure of the rotor assembly of the second embodiment of the present application;

[0023] Figure 6 Fig. 6 is a top view of the rotor assembly of the second embodiment of the present application;

[0024] Figure 7 Fig. 7 is a schematic view of the structure of the rotor assembly of the third embodiment of the present application;

[0025] Figure 8 Fig. 8 is a schematic view of the structure of the permanent magnet of the rotor assembly of the third embodiment of the present application;

[0026] Figure 9 Fig. 9 is a schematic view of the structure of the rotor assembly of the fourth embodiment of the present application;

[0027] Figure 10 Fig. 10 is a schematic view of the structure of the rotor assembly of the prior art;

[0028] Figure 11 Fig. 11 is a schematic view of the comparison between the motor of the prior art and the motor of the embodiment of the present application in terms of the effective value of the no-load line counter electromotive force;

[0029] Figure 12 Fig. 12 is a schematic view of the comparison between the motor of the prior art and the motor of the embodiment of the present application in terms of the harmonic content of the no-load line counter electromotive force;

[0030] Figure 13 Fig. 13 is a schematic view of the comparison between the motor of the prior art and the motor of the embodiment of the present application in terms of the waveform distortion rate of the no-load line counter electromotive force;

[0031] Figure 14 Fig. 14 is a schematic view of the comparison between the motor of the prior art and the motor of the embodiment of the present application in terms of the no-load cogging torque;

[0032] Figure 15 Fig. 15 is a schematic view of the comparison between the motor of the prior art and the motor of the embodiment of the present application in terms of the load electromagnetic torque;

[0033] Figure 16 Fig. 16 is a schematic view of the comparison between the motor of the prior art and the motor of the embodiment of the present application in terms of the volume of the magnetic steel and the torque density.

[0034] The reference signs are as follows:

[0035] 1 rotor core; 2 permanent magnet; 21 first transition portion; 22 second transition portion; 23 third transition portion; 24 fourth transition portion; 25 main body portion; 3 first side plane; 4 second side plane; 5 third side plane; 6 fourth side plane; 7 fifth side plane; 8 sixth side plane; 9 first protrusion; 10 second protrusion. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is only illustrative in nature and by no means as any limitation on the present application and its application or use. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present application fall within the scope of protection of the present application.

[0037] In the description of the present application, it should be understood that the orientation words such as "front, back, up, down, left, right", "transverse, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, without the opposite description, these orientation words do not indicate and imply that the indicated device or element must have a specific orientation or be constructed and operated in a specific orientation, therefore it cannot be understood as a limitation on the scope of protection of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0038] For the convenience of description, spatial relative terms such as "over", "above", "upper surface", "upper" and the like can be used herein to describe the spatial position relationship of one device or feature with other devices or features as shown in the drawings. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation of the device described in the drawings. For example, if the device in the drawings is inverted, the device described as "above" or "over" other devices or structures will be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below" orientations. The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0039] In addition, it should be noted that the use of the terms "first", "second" and the like is merely intended to distinguish the corresponding components, and the above terms do not have special meanings unless otherwise stated. Therefore, the above terms should not be interpreted as limiting the scope of protection of the present application.

[0040] With reference to Figures 1 to 16 As shown in the drawings, according to the embodiment of the present application, a rotor assembly is provided, which comprises a rotor core 1 and at least two permanent magnets 2, each of the permanent magnets 2 is attached to the outer circumferential surface of the rotor core 1, and each of the permanent magnets 2 is spaced apart along the circumferential direction of the rotor core 1, and the permanent magnet 2 comprises a first transition portion 21, a second transition portion 22 and a main body portion 25. Along the circumferential direction of the rotor core 1, the first transition portion 21 and the second transition portion 22 are respectively located at both sides of the main body portion 25, and the first transition portion 21 and the second transition portion 22 are diagonally distributed with respect to the main body portion 25, and the maximum width of the first transition portion 21 and the second transition portion 22 is less than the minimum width of the main body portion 25. Along the axial direction of the rotor core 1, the height of the first transition portion 21 and the second transition portion 22 is less than the height of the main body portion 25.

[0041] In the technical solution, since each level of the permanent magnet 2 comprises the main body portion 25 and the first transition portion 21 and the second transition portion 22 located at two opposite corners of the main body portion 25, the first transition portion 21 and the second transition portion 22 diagonally distributed between the adjacent two permanent magnets 2 will also appear. Because the height and the maximum width of the first transition portion 21 and the second transition portion 22 are respectively less than the height and the minimum width of the main body portion 25, the magnetic field strength gradually weakens from the main body portion 25 to the direction of the spacing between the adjacent two permanent magnets 2, rather than suddenly weakening, so that the movement of the center of the magnetic pole of the rotor from one stator tooth center to another stator tooth center is no longer a jump movement, but a relatively gentle movement, thereby reducing the no-load cogging torque of the motor and reducing the load torque fluctuation. At the same time, the diagonal distribution of the first transition portion 21 and the second transition portion 22 between the adjacent two permanent magnets 2 also makes the coverage range of the transition magnetic field wider, which has a good buffering effect. Further, the first transition portion 21 and the second transition portion 22 are formed by cutting part of the permanent magnet 2, which also reduces the use of the magnetic steel of the permanent magnet 2, improves the utilization rate of the magnetic steel, and improves the torque density.

[0042] It should be noted that, since the main body part 25, the first transition part 21 and the second transition part 22 are all arc-shaped structures, the inner arc surface of the main body part 25 is the region with the smallest width of the main body part 25, the outer arc surface of the main body part 25 is the region with the largest width of the main body part 25, the inner arc surface of the first transition part 21 is the region with the smallest width of the first transition part 21, the outer arc surface of the first transition part 21 is the region with the largest width of the first transition part 21, the inner arc surface of the second transition part 22 is the region with the smallest width of the second transition part 22, and the outer arc surface of the second transition part 22 is the region with the largest width of the second transition part 22. When the largest widths of the first transition part 21 and the second transition part 22 are both smaller than the smallest width of the main body part 25, it indicates that the first transition part 21 and the second transition part 22 are both narrower than the main body part 25.

[0043] As a specific embodiment, the main body part 25 has a center point, and the first transition part 21 and the second transition part 22 are centrosymmetric about the center point, which indicates that the shape and size of the first transition part 21 and the second transition part 22 are both the same. Then, between the two adjacent permanent magnets 2, the strengths of the transition magnetic fields generated by the first transition part 21 and the second transition part 22 are the same, which makes the transition magnetic field distribution more uniform, thereby being conducive to reducing the no-load cogging torque of the motor, and further being conducive to reducing the load torque fluctuation.

[0044] More specifically, the height of the main body part 25 is H1, the height of the first transition part 21 is h1, and the height of the second transition part 22 is h2, and H1≤h1+h2<2*H1.

[0045] In the embodiment, when H1≤h1+h2<2*H1, it indicates that the heights of the first transition part 21 and the second transition part 22 are reasonably set. Then, the first transition part 21 and the second transition part 22 together not only cover the entire height direction of the permanent magnet 2, which can ensure that the transition magnetic field generated between the two adjacent permanent magnets 2 is distributed in the entire height direction of the permanent magnet 2, but also makes the weakening degree of the magnetic field strength generated by the first transition part 21 and the second transition part 22 relative to the magnetic field strength generated by the main body part 25 more reasonable, and the transition of the magnetic field strength from strong to weak is relatively gentle, thereby being also conducive to reducing the no-load cogging torque of the motor, and further being conducive to reducing the load torque fluctuation.

[0046] For reference Figure 3 and Figure 6As shown, the first transition portion 21 has a first side plane 3 facing away from the main body portion 25, the second transition portion 22 has a second side plane 4 facing away from the main body portion 25, the main body portion 25 has a fifth side plane 7 on the side where the first transition portion 21 is located and a sixth side plane 8 on the side where the second transition portion 22 is located, the included angle between the first side plane 3 and the fifth side plane 7 is a1, the included angle between the second side plane 4 and the sixth side plane 8 is a2, and the included angle between the fifth side plane 7 and the sixth side plane 8 is A, 0 < (a1+a2) / A < 1.

[0047] In the technical scheme, since the main body portion 25, the first transition portion 21 and the second transition portion 22 are all arc-shaped structures, the included angle a1 between the first side plane 3 and the fifth side plane 7 can represent the width of the first transition portion 21, the included angle a2 between the second side plane 4 and the sixth side plane 8 can represent the width of the second transition portion 22, and the included angle A between the fifth side plane 7 and the sixth side plane 8 can represent the width of the main body portion 25. When 0 < (a1+a2) / A < 1, it indicates that the first transition portion 21 and the second transition portion 22 have reasonable width dimensions relative to the main body portion 25, which can make the transition of the magnetic field from strong to weak more gentle, and the buffering effect is better, thereby being more conducive to reducing the no-load cogging torque of the motor, and further more conducive to reducing the load torque fluctuation.

[0048] For reference Figures 1 to 3 As shown, the permanent magnet 2 further includes a third transition portion 23 and a fourth transition portion 24. Along the circumferential direction of the rotor core 1, the third transition portion 23 is located on the side where the first transition portion 21 faces away from the main body portion 25, and the maximum width of the third transition portion 23 is smaller than the minimum width of the first transition portion 21, and the fourth transition portion 24 is located on the side where the second transition portion 22 faces away from the main body portion 25, and the maximum width of the fourth transition portion 24 is smaller than the minimum width of the second transition portion 22. Along the axial direction of the rotor core 1, the height of the third transition portion 23 is smaller than the height of the first transition portion 21, and the height of the fourth transition portion 24 is smaller than the height of the second transition portion 22.

[0049] In the embodiment, since the third transition portion 23 is located on the side of the first transition portion 21 away from the main body portion 25, and the height and the maximum width of the third transition portion 23 are less than the height and the minimum width of the first transition portion 21 respectively, the magnetic field strength generated by the third transition portion 23 is weaker than that generated by the first transition portion 21. Since the fourth transition portion 24 is located on the side of the second transition portion 22 away from the main body portion 25, and the height and the maximum width of the fourth transition portion 24 are less than the height and the minimum width of the second transition portion 22 respectively, the magnetic field strength generated by the fourth transition portion 24 is weaker than that generated by the second transition portion 22. That is, the third transition portion 23 and the fourth transition portion 24 are equivalent to increasing the transition stroke on both sides of the permanent magnet 2, so that the transition of the magnetic field strength from strong to weak on both sides of the permanent magnet 2 is more gentle, thereby further reducing the no-load cogging torque of the motor and further reducing the load torque fluctuation. It should be noted that the third transition portion 23 and the fourth transition portion 24 are equivalent to cutting part of the permanent magnet 2, which further reduces the use of the magnetic steel of the permanent magnet 2, further improves the utilization rate of the magnetic steel, and further improves the torque density.

[0050] As a specific embodiment, the main body portion 25 has a center point, and the third transition portion 23 and the fourth transition portion 24 are centrally symmetric about the center point, which means that the third transition portion 23 and the fourth transition portion 24 have the same shape and size. Then, between the two adjacent permanent magnets 2, the transition magnetic field generated by the third transition portion 23 and the fourth transition portion 24 has the same strength, which makes the transition magnetic field distribution more uniform, thereby facilitating the reduction of the no-load cogging torque of the motor and further facilitating the reduction of the load torque fluctuation.

[0051] More specifically, the height of the main body portion 25 is H1, the height of the third transition portion 23 is h3, the height of the fourth transition portion 24 is h4, and 2 / 3*H1≤h3+h4<4 / 3*H1.

[0052] In the technical scheme, when 2 / 3*H1≤h3+h4<4 / 3*H1, it means that on the basis of the height of the third transition portion 23 being less than the height of the first transition portion 21 and the height of the fourth transition portion 24 being less than the height of the second transition portion 22, the heights of the third transition portion 23 and the fourth transition portion 24 are reasonably designed, so that the weakening degree of the magnetic field strength generated by the third transition portion 23 relative to the magnetic field strength generated by the first transition portion 21 and the weakening degree of the magnetic field strength generated by the fourth transition portion 24 relative to the magnetic field strength generated by the second transition portion 22 are reasonable, and the transition of the magnetic field strength from strong to weak is relatively gentle, thereby also facilitating the reduction of the no-load cogging torque of the motor and further facilitating the reduction of the load torque fluctuation.

[0053] For reference Figure 3 and Figure 6As shown, the third transition portion 23 has a third side plane 5 facing away from the first transition portion 21, the fourth transition portion 24 has a fourth side plane 6 facing away from the second transition portion 22, the included angle between the first side plane 3 and the third side plane 5 is a3, the included angle between the second side plane 4 and the fourth side plane 6 is a4, and the included angle between the fifth side plane 7 and the sixth side plane 8 is A, 0 < (a3+a4) / A < 0.5.

[0054] In the embodiment, since the third transition portion 23 and the fourth transition portion 24 are also arc-shaped structures, the included angle a3 between the first side plane 3 and the third side plane 5 can represent the width of the third transition portion 23, and the included angle a4 between the second side plane 4 and the fourth side plane 6 can represent the width of the fourth transition portion 24. When 0 < (a3+a4) / A < 0.5, it indicates that the widths of the third transition portion 23 and the fourth transition portion 24 are reasonably set, which can make the transition of the magnetic field from strong to weak more gentle, and the buffering effect is better, thereby being more conducive to reducing the no-load cogging torque of the motor, and further more conducive to reducing the load torque fluctuation.

[0055] For reference Figures 1 to 4 As shown, a plurality of first protrusions 9 are formed on the outer circumferential surface of the rotor core 1, each first protrusion 9 is in abutment with each first transition portion 21 along the axial direction of the rotor core 1, and each first protrusion 9 also contacts the main body portion 25.

[0056] In the technical scheme, the rotor core 1 is made of silicon steel sheets and stacked in the axial direction, each first protrusion 9 is a part of the rotor core 1, and thus the material of each first protrusion 9 is also silicon steel. Therefore, each first protrusion 9 has a magnetic aggregation effect. When each first protrusion 9 is in abutment with each first transition portion 21 along the axial direction of the rotor core 1, and each first protrusion 9 also contacts the main body portion 25, a magnetic field with a weaker magnetic field strength than that of the main body portion 25 is also generated at each first protrusion 9. In other words, the corresponding gaps of each first transition portion 21 also have a transition magnetic field, thereby expanding the range of the transition magnetic field on one side of the permanent magnet 2 along the axial direction of the rotor core 1, and more conducive to reducing the load torque fluctuation. It can be understood that when the permanent magnet 2 also includes a third transition portion 23, a stepped structure is formed on the first protrusion 9, and the first protrusion 9 is in abutment with the first transition portion 21 and the third transition portion 23 along the axial direction of the rotor core 1.

[0057] For reference Figures 1 to 4 As shown, a plurality of second protrusions 10 are also formed on the outer circumferential surface of the rotor core 1, each second protrusion 10 is in abutment with each second transition portion 22 along the axial direction of the rotor core 1, and each second protrusion 10 also contacts the main body portion 25.

[0058] In the technical solution, when each second protrusion 10 is in butt joint with each second transition portion 22 along the axial direction of the rotor core 1, and each second protrusion 10 is also in contact with the main body portion 25, a magnetic field with a weaker magnetic field strength than the main body portion 25 is also generated at each second protrusion 10, and the corresponding vacancy of each second transition portion 22 also has a transition magnetic field, so that the range of the transition magnetic field on the other side of the permanent magnet 2 along the axial direction of the rotor core 1 is enlarged, and the load torque fluctuation is more favorably reduced. It can be understood that when the permanent magnet 2 further includes a fourth transition portion 24, a stepped structure is formed on the second protrusion 10, and the second protrusion 10 is in butt joint with the second transition portion 22 and the fourth transition portion 24 along the axial direction of the rotor core 1.

[0059] It also needs to be noted that the permanent magnet 2 can be integrally formed by the main body portion 25, the first transition portion 21, the second transition portion 22, the third transition portion 23 and the fourth transition portion 24, as shown in Figs. Figure 1 、 Figure 2 、 Figure 3 and Figure 5 . As another embodiment, the main body portion 25, the first transition portion 21, the second transition portion 22, the third transition portion 23 and the fourth transition portion 24 can also be separate arc-shaped magnetic steel blocks, that is, the permanent magnet 2 can also be formed by splicing a plurality of arc-shaped magnetic steel blocks, as shown in Fig. Figures 7 to 9 . When the permanent magnet 2 is formed by splicing a plurality of arc-shaped magnetic steel blocks, the magnetization directions of all the magnetic steel blocks in the same pole are the same.

[0060] As a specific embodiment, along the axial direction of the rotor core 1, the height of the rotor core 1 is H2, and the height of the main body portion 25 is H1, and H1≤1.3*H2. When the height of the main body portion 25 and the height of the rotor core 1 satisfy the condition, the magnetic steel utilization rate can be further improved, so that the torque density is further improved.

[0061] Figures 11 to 16 Fig. 6 shows the comparison of the performance of the motor of the prior art and the motor of the embodiment of the present application. The experimental data show that, compared with the motor of the prior art, the motor of the embodiment of the present application has only a 2.0% decrease in the effective value of the no-load line counter electromotive force, but the 5th and 7th harmonic contents are significantly reduced; the waveform distortion rate of the no-load line counter electromotive force is reduced by about 48%; the no-load cogging torque is reduced by about 82%, the average value of the load electromagnetic torque is only reduced by 2.43%, but the torque fluctuation is reduced by 73.7%; the amount of magnetic steel is reduced by 5.5%, and the electromagnetic torque density of the unit volume of the magnetic steel is increased by 3.26%. The above data show that the performance of the motor of the embodiment of the present application is obviously improved, the cost is also reduced, and the performance-price ratio of the motor is improved.

[0062] The present application also provides a motor comprising the aforementioned rotor assembly, and the motor of the present application particularly refers to a permanent magnet synchronous motor.

[0063] Those skilled in the art can easily understand that the advantageous technical features of the above-mentioned modes can be freely combined and superimposed without conflict.

[0064] The above is only the preferred embodiment of the present application, and should be pointed out that, for ordinary skilled in the art, without departing from the technical principles of the present application, can also make a number of improvements and variations, these improvements and variations should be considered as the protection scope of the present application.

Claims

1. A rotor assembly characterized by, The rotor core (1) and at least two permanent magnets (2), each of the permanent magnets (2) is attached to the outer circumferential surface of the rotor core (1), and each of the permanent magnets (2) is spaced along the circumference of the rotor core (1), the permanent magnet (2) comprises a first transition part (21), a second transition part (22) and a main body part (25); Along the circumference of the rotor core (1), the first transition part (21) and the second transition part (22) are respectively located on both sides of the main body part (25), and the first transition part (21) and the second transition part (22) are diagonally distributed relative to the main body part (25), the maximum width of the first transition part (21) and the second transition part (22) is less than the minimum width of the main body part (25); Along the axial direction of the rotor core (1), the height of the first transition part (21) and the second transition part (22) is less than the height of the main body part (25); The first transition part (21) has a first side plane (3) facing away from the main body part (25), the second transition part (22) has a second side plane (4) facing away from the main body part (25), the main body part (25) has a fifth side plane (7) on the side of the first transition part (21) and a sixth side plane (8) on the side of the second transition part (22), the included angle between the first side plane (3) and the fifth side plane (7) is a1, the included angle between the second side plane (4) and the sixth side plane (8) is a2, and the included angle between the fifth side plane (7) and the sixth side plane (8) is A, 0 < (a1+a2) / A < 1.

2. The rotor assembly of claim 1, wherein The main body part (25) has a center point, and the first transition part (21) and the second transition part (22) are centrally symmetric about the center point.

3. The rotor assembly of claim 1 or 2, wherein, The height of the main body part (25) is H1, the height of the first transition part (21) is h1, and the height of the second transition part (22) is h2, H1≤h1+h2<2*H1.

4. The rotor assembly of claim 1, wherein The permanent magnet (2) further comprises a third transition part (23) and a fourth transition part (24); Along the circumference of the rotor core (1), the third transition part (23) is located on the side of the first transition part (21) facing away from the main body part (25), and the maximum width of the third transition part (23) is less than the minimum width of the first transition part (21), and the fourth transition part (24) is located on the side of the second transition part (22) facing away from the main body part (25), and the maximum width of the fourth transition part (24) is less than the minimum width of the second transition part (22); Along the axial direction of the rotor core (1), the height of the third transition part (23) is less than the height of the first transition part (21), and the height of the fourth transition part (24) is less than the height of the second transition part (22).

5. The rotor assembly of claim 4, wherein The main body part (25) has a center point, and the third transition part (23) and the fourth transition part (24) are centrally symmetric about the center point.

6. A rotor assembly according to claim 4 or 5, characterised in that The height of the main body part (25) is H1, the height of the third transition part (23) is h3, the height of the fourth transition part (24) is h4, 2 / 3*H1≤h3+h4<4 / 3*H1.

7. The rotor assembly of claim 4 or 5, wherein, The first transition part (21) has a first side plane (3) facing away from the main body part (25), the second transition part (22) has a second side plane (4) facing away from the main body part (25), the third transition part (23) has a third side plane (5) facing away from the first transition part (21), the fourth transition part (24) has a fourth side plane (6) facing away from the second transition part (22), the main body part (25) has a fifth side plane (7) on the side where the first transition part (21) is located and a sixth side plane (8) on the side where the second transition part (22) is located, the included angle between the first side plane (3) and the third side plane (5) is a3, the included angle between the second side plane (4) and the fourth side plane (6) is a4, and the included angle between the fifth side plane (7) and the sixth side plane (8) is A, 0<(a3+a4) / A<0.

5.

8. The rotor assembly of claim 1, wherein A plurality of first protrusions (9) are formed on the outer circumferential surface of the rotor core (1), each of the first protrusions (9) is in abutment with each of the first transition parts (21) along the axial direction of the rotor core (1), and each of the first protrusions (9) is in contact with the main body part (25); and / or, a plurality of second protrusions (10) are formed on the outer circumferential surface of the rotor core (1), each of the second protrusions (10) is in abutment with each of the second transition parts (22) along the axial direction of the rotor core (1), and each of the second protrusions (10) is in contact with the main body part (25).

9. The rotor assembly of claim 1, wherein Along the axial direction of the rotor core (1), the height of the rotor core (1) is H2, and the height of the main body part (25) is H1, H1≤1.3*H2.

10. An electric machine characterized by A rotor assembly comprising the rotor assembly of any one of claims 1 to 9.

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