Rotor assembly and motor with same

Abstract

The invention provides a rotor assembly and a motor having the same, the rotor assembly comprises a rotor core and a plurality of permanent magnets which are surface-mounted on the outer peripheral surface of the rotor core and are distributed at intervals, each permanent magnet comprises a first transition part, a second transition part and a main body part, and the first transition part and the second transition part are respectively located at two sides of the main body part. The first transition part and the second transition part are diagonally distributed relative to the main body part, the maximum width of the first transition part and the maximum width of the second transition part are both smaller than the minimum width of the main body part, and the height of the first transition part and the height of the second transition part are both smaller than the height of the main body part. According to the invention, each permanent magnet comprises the main body part, and the first transition part and the second transition part which are positioned at the two opposite angles of the main body part, so that the magnetic field intensity is gradually weakened in the direction from the main body part to the distance between the two adjacent permanent magnets instead of being suddenly weakened in a cliff manner, and therefore, the no-load cogging torque can be reduced; and the load torque fluctuation is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and in particular relates to a rotor assembly and a motor having the same. Background Art

[0002] Permanent magnet synchronous motors have excellent energy-saving effects and are widely used in the industrial field. Torque density is an important indicator to measure the performance of permanent magnet synchronous motors, and cogging torque will affect the position control accuracy, noise and vibration performance of permanent magnet synchronous motors. Therefore, it is very necessary to improve torque density and optimize cogging torque for permanent magnet synchronous motors and servo control systems. At present, the arrangement of each surface-mounted permanent magnet on the rotor core of the traditional surface-mounted permanent magnet synchronous motor is as follows: Fig.10 As shown, since the permanent magnets of each pole are regular arc-shaped bodies, that is, the projections of the two ends of the permanent magnets of each pole in the axial direction overlap with each other, and there is a constant width of spacing between two adjacent permanent magnets (air is in the spacing), the magnetic field intensity at the spacing is suddenly and significantly weakened relative to the magnetic field intensity at the center of the magnetic pole, which makes the movement of the magnetic pole center of the rotor from one stator tooth center to another stator tooth center a jumping movement, resulting in large tooth slot torque pulsation of the motor and large load torque fluctuation. Summary of the invention

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

[0004] In order to solve the above problems, the present invention provides a rotor assembly, including a rotor core and at least two permanent magnets, each of the permanent magnets is attached to the outer circumferential surface of the rotor core, and each of the permanent magnets is distributed at intervals along the circumferential direction of the rotor core, and the permanent magnet includes a first transition portion, a second transition portion and a main body portion; along the circumference of the rotor core, the first transition portion and the second transition portion are respectively located on both sides of the main body portion, and the first transition portion and the second transition portion are diagonally distributed relative to the main body portion, and the maximum width of the first transition portion and the second transition portion are both smaller than the minimum width of the main body portion; along the axial direction of the rotor core, the height of the first transition portion and the second transition portion are both smaller than the height of the main body portion.

[0005] In some embodiments, the main body portion 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, and H1≤h1+h2<2*H1.

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

[0008] In some embodiments, the permanent magnet also includes a third transition portion and a fourth transition portion; along the circumference of the rotor core, the third transition portion is located on the side of the first transition portion facing away from the main body portion, and the maximum width of the third transition portion is smaller than the minimum width of the first transition portion, and the fourth transition portion is located on the side of the second transition portion facing away from the main body portion, and the maximum width of the fourth transition portion is smaller than the minimum width of the second transition portion; along the axial direction of the rotor core, the height of the third transition portion is smaller than the height of the first transition portion, and the height of the fourth transition portion is smaller than the height of the second transition portion.

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

[0010] In some embodiments, the height of the main body is H1, the height of the third transition portion is h3, the height of the fourth transition portion is h4, and 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 body portion, the second transition portion has a second side plane facing away from the main body 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 body portion has a fifth side plane on the side where the first transition portion is located and a sixth side plane on the side where the second transition portion is located, the angle formed between the first side plane and the third side plane is a3, the angle formed between the second side plane and the fourth side plane is a4, the angle formed 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 respectively connected to the first transition portion along the axial direction of the rotor core, and each of the first protrusions is also in contact with the main body; and / or a plurality of second protrusions are also formed on the outer circumferential surface of the rotor core, each of the second protrusions is respectively connected to the second transition portion along the axial direction of the rotor core, and each of the second protrusions is also in contact with the main body.

[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 is H1, and H1≤1.3*H2.

[0014] The present invention also provides a motor, comprising the above-mentioned rotor assembly.

[0015] The present invention provides a rotor assembly and a motor having the same, which have the following beneficial effects:

[0016] Since the permanent magnets of each level of the present application include a main body and a first transition part and a second transition part at two diagonal positions of the main body, a diagonally distributed first transition part and a second transition part will also appear between two adjacent permanent magnets. Because the height and maximum width of the first transition part and the second transition part are respectively smaller than the height and minimum width of the main body, the magnetic field strength in the direction from the main body to the spacing between two adjacent permanent magnets presents a gradually weakening trend, rather than a sudden cliff-like weakening, so the movement of the magnetic pole center of the rotor from one stator tooth center to another stator tooth center is no longer a jumping movement, but a relatively gentle movement, thereby reducing the no-load tooth slot torque of the motor and reducing the load torque fluctuation. At the same time, the first transition part and the second transition part are also diagonally distributed between two adjacent permanent magnets, so that the coverage of the transition magnetic field is wider and the buffering effect is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0018] Figure 1 It is a structural schematic diagram of a rotor assembly according to Embodiment 1 of the present invention;

[0019] Figure 2 is a schematic diagram of a permanent magnet of a rotor assembly according to a first embodiment of the present invention;

[0020] Figure 3is a schematic diagram of a permanent magnet of a rotor assembly according to Embodiment 1 of the present invention from another viewing angle;

[0021] Figure 4 It is a schematic structural diagram of a rotor core of a rotor assembly according to Embodiment 1 of the present invention;

[0022] Figure 5 is a schematic structural diagram of a rotor assembly according to a second embodiment of the present invention;

[0023] Figure 6 is a top view of a rotor assembly according to a second embodiment of the present invention;

[0024] Figure 7 is a schematic structural diagram of a rotor assembly according to a third embodiment of the present invention;

[0025] Figure 8 This is a schematic structural diagram of a permanent magnet of a rotor assembly according to Embodiment 3 of the present invention;

[0026] Fig. 9 Schematic diagram of the structure of the rotor assembly of the fourth embodiment of the present invention;

[0027] Fig.10 It is a structural schematic diagram of a rotor assembly in the prior art;

[0028] Fig.11 A schematic diagram showing a comparison of the effective value of the no-load line back electromotive force between a motor in the prior art and a motor in an embodiment of the present invention;

[0029] Fig.12 It is a schematic diagram comparing the harmonic content of no-load line back-EMF between the motor of the prior art and the motor of the embodiment of the present invention;

[0030] Fig.13 A schematic diagram comparing the no-load line back-EMF waveform distortion rate of a motor in the prior art and a motor in an embodiment of the present invention;

[0031] Fig.14 A schematic diagram comparing no-load cogging torque between a motor in the prior art and a motor in an embodiment of the present invention;

[0032] Fig.15 A schematic diagram comparing the load electromagnetic torque of a motor in the prior art and a motor in an embodiment of the present invention;

[0033] Fig.16 It is a schematic diagram comparing the magnetic steel volume and torque density of the motor of the prior art and the motor of the embodiment of the present invention.

[0034] The reference numerals are:

[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; 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 following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0038] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0039] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0040] See also Figures 1 to 16 As shown, according to an embodiment of the present invention, a rotor assembly is provided, comprising a rotor core 1 and at least two permanent magnets 2, each of which is attached to the outer circumferential surface of the rotor core 1, and each of which 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 25. Along the circumferential direction of the rotor core 1, the first transition portion 21 and the second transition portion 22 are respectively located on both sides of the main body 25, and the first transition portion 21 and the second transition portion 22 are diagonally distributed relative to the main body 25, and the maximum width of the first transition portion 21 and the second transition portion 22 are both smaller than the minimum width of the main body 25. Along the axial direction of the rotor core 1, the height of the first transition portion 21 and the second transition portion 22 are both smaller than the height of the main body 25.

[0041] In this technical solution, since each level of permanent magnet 2 includes a main body 25 and a first transition part 21 and a second transition part 22 at two diagonal positions of the main body 25, a diagonally distributed first transition part 21 and a second transition part 22 will also appear between two adjacent permanent magnets 2. Because the height and maximum width of the first transition part 21 and the second transition part 22 are respectively smaller than the height and minimum width of the main body 25, the magnetic field strength in the direction from the main body 25 to the spacing between two adjacent permanent magnets 2 shows a gradually weakening trend, rather than a sudden cliff-like weakening, so the movement of the magnetic pole center of the rotor from one stator tooth center to another stator tooth center is no longer a jumping 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 diagonally distributed state of the first transition part 21 and the second transition part 22 between two adjacent permanent magnets 2 also makes the coverage of the transition magnetic field wider, and has a better buffering effect. Furthermore, the first transition portion 21 and the second transition portion 22 are equivalent to being formed by partially cutting off the permanent magnet 2 , which also reduces the amount of magnetic steel used in the permanent magnet 2 , improves the utilization rate of the magnetic steel, and enhances the torque density.

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

[0043] As a specific implementation, the main body 25 has a center point, and the first transition portion 21 and the second transition portion 22 are symmetrical about the center point, which indicates that the first transition portion 21 and the second transition portion 22 are of the same shape and size. Then, between two adjacent permanent magnets 2, the strength of the transition magnetic field generated by the first transition portion 21 and the second transition portion 22 is the same, which makes the transition magnetic field more evenly distributed, thereby facilitating the reduction of the no-load cogging torque of the motor, and further facilitating the reduction of load torque fluctuations.

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

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

[0046] See also 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 angle formed between the first side plane 3 and the fifth side plane 7 is a1, the angle formed between the second side plane 4 and the sixth side plane 8 is a2, and the angle formed between the fifth side plane 7 and the sixth side plane 8 is A, 0<(a1+a2) / A<1.

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

[0048] See also 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 of the first transition portion 21 facing 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 of the second transition portion 22 facing 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 this embodiment, since the third transition portion 23 is located on the side of the first transition portion 21 facing away from the main body 25, and the height and maximum width of the third transition portion 23 are respectively smaller than the height and minimum width of the first transition portion 21, the magnetic field intensity generated by the third transition portion 23 is weaker than the magnetic field intensity generated by the first transition portion 21. In addition, since the fourth transition portion 24 is located on the side of the second transition portion 22 facing away from the main body 25, and the height and maximum width of the fourth transition portion 24 are respectively smaller than the height and minimum width of the second transition portion 22, the magnetic field intensity generated by the fourth transition portion 24 is weaker than the magnetic field intensity generated by the second transition portion 22. That is, the arrangement of the third transition portion 23 and the fourth transition portion 24 is equivalent to increasing the transition stroke on both sides of the permanent magnet 2, so that the magnetic field intensity on both sides of the permanent magnet 2 transitions from strong to weak more smoothly, 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 also formed by partially cutting off the permanent magnet 2, which further reduces the amount of magnetic steel used in the permanent magnet 2, further improves the utilization rate of the magnetic steel, and further improves the torque density.

[0050] As a specific implementation, the main body 25 has a center point, and the third transition portion 23 and the fourth transition portion 24 are symmetrical about the center point, which indicates that the third transition portion 23 and the fourth transition portion 24 have the same shape and size. Then, between two adjacent permanent magnets 2, the strength of the transition magnetic field generated by the third transition portion 23 and the fourth transition portion 24 is the same, which makes the transition magnetic field more evenly distributed, thereby facilitating the reduction of the no-load cogging torque of the motor, and further facilitating the reduction of load torque fluctuations.

[0051] More specifically, the height of the main body 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 this technical solution, when 2 / 3*H1≤h3+h4<4 / 3*H1, it indicates that on the basis that the height of the third transition portion 23 is less than the height of the first transition portion 21 and the height of the fourth transition portion 24 is 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 magnetic field strength generated by the third transition portion 23 is weakened by a reasonable amplitude relative to the magnetic field strength generated by the first transition portion 21, and the magnetic field strength generated by the fourth transition portion 24 is weakened by a reasonable amplitude relative to the magnetic field strength generated by the second transition portion 22, and the transition of the magnetic field strength from strong to weak is relatively smooth, which is also beneficial to reducing the no-load cogging torque of the motor, and further beneficial to reducing load torque fluctuations.

[0053] See also 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 angle formed between the first side plane 3 and the third side plane 5 is a3, the angle formed between the second side plane 4 and the fourth side plane 6 is a4, the angle formed between the fifth side plane 7 and the sixth side plane 8 is A, 0<(a3+a4) / A<0.5.

[0054] In this embodiment, since the third transition portion 23 and the fourth transition portion 24 are also arc-shaped structures, the angle a3 formed between the first side plane 3 and the third side plane 5 can represent the width of the third transition portion 23, and the angle a4 formed 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 from strong to weak magnetic field smoother and have better buffering effect, thereby being more conducive to reducing the no-load cogging torque of the motor, and further being more conducive to reducing load torque fluctuation.

[0055] See also 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 respectively connected with each first transition portion 21 along the axial direction of the rotor core 1 , and each first protrusion 9 is also in contact with the main body 25 .

[0056] In this technical solution, the rotor core 1 is formed by axially stacking silicon steel sheets, and each first protrusion 9 is a part of the rotor core 1. Therefore, the material of each first protrusion 9 is also silicon steel, and each first protrusion 9 has a magnetic field gathering effect. When each first protrusion 9 is connected with each first transition part 21 along the axial direction of the rotor core 1, and each first protrusion 9 is also in contact with the main body 25, a magnetic field with a weaker magnetic field intensity than the main body 25 is generated at each first protrusion 9, which is equivalent to the vacancy corresponding to each first transition part 21 also having a transition magnetic field, so that one side of the permanent magnet 2 expands the range of the transition magnetic field along the axial direction of the rotor core 1, which is more conducive to reducing the load torque fluctuation. It can be understood that when the permanent magnet 2 also includes the third transition part 23, a step structure is formed on the first protrusion 9, and the first protrusion 9 is connected with the first transition part 21 and the third transition part 23 at the same time along the axial direction of the rotor core 1.

[0057] See also Figures 1 to 4 As shown, a plurality of second protrusions 10 are formed on the outer circumferential surface of the rotor core 1 , and each second protrusion 10 is respectively connected 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 25 .

[0058] In this technical solution, when each second protrusion 10 is connected to each second transition part 22 along the axial direction of the rotor core 1, and each second protrusion 10 is also in contact with the main body 25, a magnetic field with a weaker magnetic field strength than that of the main body 25 is generated at each second protrusion 10, which is equivalent to the vacancy corresponding to each second transition part 22 also having a transition magnetic field, thereby expanding 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, which is more conducive to reducing load torque fluctuations. It can be understood that when the permanent magnet 2 also includes the fourth transition part 24, a step structure is formed on the second protrusion 10, and the second protrusion 10 is connected to the second transition part 22 and the fourth transition part 24 at the same time along the axial direction of the rotor core 1.

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

[0060] As a specific implementation, along the axial direction of the rotor core 1, the height of the rotor core 1 is H2, the height of the main body 25 is H1, and H1≤1.3*H2. When the height of the main body 25 and the height of the rotor core 1 meet this condition, the utilization rate of the magnetic steel can be further improved, thereby further improving the torque density.

[0061] Figures 11 to 16 The figure shows a comparison of various aspects of the performance of the motor of the prior art and the motor of the embodiment of the present invention. Experimental data show that compared with the motor of the prior art, the effective value of the no-load line back EMF of the motor of the embodiment of the present invention only decreases by 2.0%, but the 5th and 7th harmonic contents are significantly reduced; the waveform distortion rate of the no-load line back EMF decreases by about 48%; the no-load cogging torque decreases by about 82%, the mean value of the load electromagnetic torque only decreases by 2.43%, but the torque fluctuation decreases by 73.7%; the amount of magnetic steel is reduced by 5.5%, and the electromagnetic torque density of the magnetic steel per unit volume is increased by 3.26%. The above data show that the performance of the motor of the embodiment of the present invention is significantly improved, the cost is correspondingly reduced, and the cost performance of the motor is improved.

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

[0063] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0064] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A rotor assembly, characterized in that: The invention comprises a rotor core (1) and at least two permanent magnets (2), each of the permanent magnets (2) being attached to the outer peripheral surface of the rotor core (1), and each of the permanent magnets (2) being distributed at intervals along the circumference of the rotor core (1), and each of the permanent magnets (2) comprising 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 on both sides of the main body (25), and the first transition portion (21) and the second transition portion (22) are diagonally distributed relative to the main body (25), and the maximum widths of the first transition portion (21) and the second transition portion (22) are both smaller than the minimum width of the main body (25); Along the axial direction of the rotor core (1), the heights of the first transition portion (21) and the second transition portion (22) are both smaller than the height of the main body portion (25).

2. The rotor assembly according to claim 1, characterized in that The main body portion (25) has a center point, and the first transition portion (21) and the second transition portion (22) are centrally symmetrical about the center point.

3. The rotor assembly according to claim 1 or 2, characterized in that: The height of the main body (25) is H1, the height of the first transition portion (21) is h1, and the height of the second transition portion (22) is h2, H1≤h1+h2<2*H1.

4. The rotor assembly according to claim 1 or 2, characterized in that: 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) located on the side where the first transition portion (21) is located, and a sixth side plane (8) located on the side where the second transition portion (22) is located, the angle formed between the first side plane (3) and the fifth side plane (7) is a1, the angle formed between the second side plane (4) and the sixth side plane (8) is a2, and the angle formed between the fifth side plane (7) and the sixth side plane (8) is A, 0<(a1+a2) / A<1.

5. The rotor assembly according to claim 1, characterized in that: The permanent magnet (2) further comprises 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 a side of the first transition portion (21) facing 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); the fourth transition portion (24) is located on a side of the second transition portion (22) facing 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).

6. The rotor assembly according to claim 5, characterized in that The main body portion (25) has a center point, and the third transition portion (23) and the fourth transition portion (24) are centrally symmetrical about the center point.

7. The rotor assembly according to claim 5 or 6, characterized in that: The height of the main body (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.

8. The rotor assembly according to claim 5 or 6, characterized in that: 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 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 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 angle formed between the first side plane (3) and the third side plane (5) is a3, the angle formed between the second side plane (4) and the fourth side plane (6) is a4, and the angle formed between the fifth side plane (7) and the sixth side plane (8) is A, 0<(a3+a4) / A<0.

5.

9. The rotor assembly according to claim 1, characterized in that: A plurality of first protrusions (9) are formed on the outer circumferential surface of the rotor core (1), and each of the first protrusions (9) is respectively connected to each of the first transition parts (21) along the axial direction of the rotor core (1), and each of the first protrusions (9) is also in contact with the main body (25); and / or a plurality of second protrusions (10) are also formed on the outer circumferential surface of the rotor core (1), and each of the second protrusions (10) is respectively connected to each of the second transition parts (22) along the axial direction of the rotor core (1), and each of the second protrusions (10) is also in contact with the main body (25).

10. The rotor assembly according to claim 1, characterized in that Along the axial direction of the rotor core (1), the height of the rotor core (1) is H2, the height of the main body (25) is H1, and H1≤1.3*H2.

11. A motor, characterized in that: A rotor assembly comprising any one of claims 1 to 10.

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