Rotor for electric machine, electric machine and method for manufacturing rotor for electric machine

Abstract

The present invention relates to a rotor for an electric machine, comprising: a magnetic core comprising a plurality of neodymium iron boron magnets arranged at intervals along a rotation axis of the rotor; a support device provided at both axial sides of the magnetic core along the rotation axis and supporting the magnetic core; and a sleeve made of a non-metallic material and disposed radially outward of the magnetic core around the magnetic core, in which the electrical resistivity of the sleeve is between # imgabs 0 # and # imgabs 1 #, in which the support device and the magnetic core are fixed together by the sleeve and are rotatable together around a rotational axis. The rotor can reduce the eddy current loss of the magnetic core and the sleeve, and further can reduce the air gap of the motor, thereby facilitating the improvement of the power density of the motor, and reducing the size of the motor. In addition, the rotor can significantly reduce the material and processing cost without reducing the performance of the motor. The invention further relates to an electric machine and to a method for producing a rotor for an electric machine.

Description

Technical Field

[0001] The present invention relates to a rotor for an electric motor, particularly for a high-speed electric motor. Additionally, the present invention also relates to an electric motor and a method for manufacturing a rotor for an electric motor. Background Art

[0002] High-speed electric motors (or high-speed rotating electric motors) have a wide range of industrial applications. For example, high-speed electric motors can be used as compressor motors, energy storage flywheel motors, or motors for power tools, etc., to provide the driving force required for high-speed rotation of components such as impellers. The motors of centrifugal compressors can typically reach speeds of 80,000 revolutions per minute (rpm) or higher. Currently, in order to achieve stable performance output of the electric motor at high temperatures, most high-speed electric motors may choose a design solution where the rotor includes samarium cobalt (SmCo) magnets. However, due to the scarcity of raw materials, the price of samarium cobalt is relatively high. Additionally, in the application of high-speed electric motors, samarium cobalt magnets are usually used in conjunction with Inconel sleeves. The processing cost of Inconel alloy materials is also quite high, which further increases the cost of manufacturing high-speed electric motors.

[0003] Furthermore, due to the good electrical conductivity of Inconel alloy, when the electric motor is operating, eddy currents will be generated in this sleeve in an alternating magnetic field, and the heat generated by these eddy currents will also reduce the output power of the electric motor.

[0004] Therefore, it is necessary to improve the structure of the existing rotor in order to provide an improved electric motor that can overcome one or more drawbacks existing in the prior art. Summary of the Invention

[0005] The object of the present invention is to provide a rotor for an electric motor, particularly for a high-speed electric motor, where the rotor of the high-speed electric motor can significantly reduce the amount of magnets used, reduce material and processing costs, without reducing the performance of the electric motor. Additionally, the electric motor can reduce the eddy currents and the temperature of the rotor core generated during operation, thereby increasing the output power of the electric motor.

[0006] According to a first aspect of the present invention, a rotor for an electric motor is proposed, which may include: a magnetic core, the magnetic core may include a plurality of neodymium iron boron magnets arranged at intervals along the rotation axis of the rotor; a support device, the support device may be arranged on both axial sides of the magnetic core along the rotation axis and support the magnetic core; and a sleeve, the sleeve may be made of a non-metallic material and disposed around the magnetic core on the radial outside of the magnetic core, wherein the resistivity of the sleeve is between and wherein the support device and the magnetic core are fixed together by the sleeve and can rotate together around the rotation axis.

[0007] This kind of rotor can reduce the eddy current loss of the magnetic core and the sleeve, and thus can reduce the air gap of the motor, which helps to improve the power density and output power of the motor and reduce the volume of the motor.

[0008] In addition, the inventors of the present application have determined through experiments that, taking a motor with a rated power of 30 kW and a rotational speed of 90,000 revolutions per minute as an example, compared with the rotor using samarium cobalt magnets in the prior art, the rotor according to the present invention can reduce the usage amount of magnets by at least 24%, and at the same time can ensure the same or slightly higher output power of the motor, thus significantly reducing the material and processing costs without reducing the performance of the motor.

[0009] According to the above aspects of the present invention, preferably, adjacent magnets among the plurality of neodymium iron boron magnets of the magnetic core can be fixed together via an insulating adhesive.

[0010] In this way, the interval between adjacent magnets can be further reduced, the eddy current loss can be reduced, and the power density can be improved.

[0011] According to the above aspects of the present invention, preferably, the supporting device can include a first supporting member, an opposite second supporting member, and a pillar extending between the first supporting member and the second supporting member, wherein the magnetic core can include a central opening, and the pillar can extend through the central opening to support the magnetic core on the supporting device.

[0012] In this way, the alignment of the segmented magnets can be conveniently and reliably achieved, the space occupied by additional fixing devices can be reduced, and thus the power density of the motor can be further increased.

[0013] According to the above aspects of the present invention, preferably, the pillar and the first supporting member can be integrally formed, and the second supporting member can be provided with a supporting hole, and the free end of the pillar can extend into the supporting hole.

[0014] In this way, the concentricity / coaxiality of the supporting device and the magnetic core can be better achieved, thereby reducing the runout or imbalance during the rotation of the rotor.

[0015] According to the above aspects of the present invention, preferably, the outer surfaces of the first supporting member and the second supporting member can be pre-coated with chromium nitride or titanium nitride.

[0016] By coating chromium nitride or titanium nitride, friction is reduced and wear is resisted, material loss is reduced, the reliability of the rotor during high-speed rotation is ensured, and the temperature rise caused by friction is reduced.

[0017] According to the above aspects of the present invention, preferably, the sleeve can be made of a carbon fiber material.

[0018] This sleeve can significantly increase the strength of the rotor to adapt to high-speed rotation conditions, and at the same time can further reduce eddy current losses, and reduce the air gap by reducing the thickness of the material used, thereby increasing the power density of the motor.

[0019] According to the above aspects of the present invention, preferably, the magnetic core can be press-fitted into the sleeve or carbon fiber material can be wound around the magnetic core and cured to form an interference fit between the magnetic core and the sleeve.

[0020] In this way, no additional fixing devices or processes, such as welding or fastener connection, etc., are required, further reducing the weight of the rotor and increasing the strength and reliability of the rotor.

[0021] According to the above aspects of the present invention, preferably, each magnet in the magnetic core can have a cylindrical shape, and the axial length of the magnetic core is between 30 mm and 80 mm, while the diameter of the magnetic core is between 10 mm and 50 mm.

[0022] Through this arrangement, the centrifugal force experienced by the rotor during high-speed rotation can be reduced, especially the centrifugal force of the part farther from the rotation axis, thereby allowing the magnetic core to be directly formed by neodymium iron boron magnets without additional magnetic steel and other holding structures.

[0023] According to the above aspects of the present invention, in order to better achieve the balance between motor efficiency and magnet loss, preferably, the magnetic core can include 3-10 magnets arranged at intervals along the rotation axis.

[0024] According to the second aspect of the present invention, a motor is proposed. The motor can be a permanent magnet synchronous motor and can include: a rotor according to the above aspects; and a stator, which is arranged around the rotor and is arranged on the radial outside of the rotor. Among them, the rotational speed of the rotor is between 40,000 revolutions per minute and 200,000 revolutions per minute, and preferably, between 50,000 revolutions per minute and 150,000 revolutions per minute.

[0025] This kind of motor can be applied to high-speed industrial applications such as centrifugal compressors, has a high power density and motor efficiency, and has low noise.

[0026] According to the third aspect of the present invention, a method for manufacturing a rotor for a motor is proposed. The method can include the following steps: providing a magnetic core, which can include a plurality of neodymium iron boron magnets; fixing the plurality of neodymium iron boron magnets together along the axial direction, and arranging each of the plurality of neodymium iron boron magnets at intervals along the rotation axis of the rotor; installing the magnetic core on a supporting device, and the supporting device can be arranged on both axial sides of the magnetic core along the rotation axis; arranging a sleeve around the magnetic core, and the sleeve is made of a non-metallic material and is arranged around the magnetic core on the radial outside of the magnetic core. Among them, the resistivity of the sleeve is in to Therein, the sleeve fixes the supporting device and the magnetic core together and is capable of rotating together about the rotation axis. The rotor manufactured by this method can reduce the eddy current loss of the magnetic core and the sleeve, and thus can reduce the air gap of the motor, which helps to improve the power density of the motor and reduce the volume of the motor.

[0027] According to the above aspect of the present invention, preferably, adjacent magnets among the plurality of neodymium iron boron magnets are fixed together via an insulating adhesive, and the plurality of neodymium iron boron magnets are placed in a heating device to cure the insulating adhesive.

[0028] In this way, the interval between adjacent magnets can be further reduced, the structural strength of the magnets and the rotor is enhanced, and the eddy current loss is reduced, and the power density is improved.

[0029] According to the above aspect of the present invention, preferably, before assembling the magnetic core into the sleeve, at least a part of the outer surfaces of the magnetic core and the supporting device is ground, and then the magnetic core and the supporting device are press-fitted into the sleeve.

[0030] In this way, no additional fixing devices or processes, such as welding or fastener connection, etc., are required, further reducing the weight of the rotor and increasing the strength and reliability of the rotor.

[0031] According to the above aspect of the present invention, preferably, the sleeve can be made of a carbon fiber material, and the carbon fiber material is woven around the magnetic core and cured to form a sleeve fixed to the magnetic core.

[0032] In this way, no additional fixing devices or processes are required. On the other hand, the overall structural strength of the rotor can be further improved.

[0033] According to the above aspect of the present invention, preferably, the method may further include: a step of performing a dynamic balancing operation on the rotor; and a step of magnetizing the magnetic core.

[0034] Thus, the rotor for an electric motor according to the present invention can meet the usage requirements, overcomes the disadvantages of the prior art and achieves the predetermined purpose. Description of the Drawings

[0035] In order to further clearly describe the rotor for an electric motor according to the present invention, the present invention will be described in detail below in conjunction with the drawings and specific embodiments. In the drawings: Figure 1 A cross-sectional schematic view of an electric motor showing a non-limiting embodiment according to the present invention is shown; Figure 2 A schematic cross-sectional view of a rotor for an electric motor showing a non-limiting embodiment according to the present invention is shown; Figure 3Shows the relationship between the number of magnet segments of the rotor according to the present invention and magnet loss and motor efficiency; Figure 4 Shows a schematic cross-sectional view of a motor of the prior art; and Figure 5 Shows a schematic cross-sectional view of a motor according to a non-limiting embodiment of the present invention.

[0036] The above-mentioned drawings are merely schematic and are not drawn strictly to scale.

[0037] List of reference numerals in the drawings and embodiments: 1000 - Motor, including: 100 - Rotor, including: 10 - Magnetic core, including: 10A - Central opening; 20 - Support device, including: 21 - First support member, including 211 - First bearing portion; 212 - First mounting portion; 22 - Second support member, including: 221 - Second bearing portion; 222 - Second mounting portion; 22A - Support hole: 23 - Strut; 23A - Free end; 30 - Sleeve; 200 - Stator; 300 - Air gap; X - Axis of rotation. Detailed description of the invention

[0038] It should be understood that unless explicitly stated to the contrary, the present invention may adopt various alternative orientations and step sequences. It should also be understood that the specific devices shown in the drawings and described in the specification are merely exemplary embodiments of the inventive concept disclosed and defined herein. Thus, unless otherwise explicitly stated, the specific orientations, directions or other features related to the various disclosed embodiments should not be considered limiting.

[0039] Figure 1 Shows a schematic cross-sectional view of a motor 1000 according to a non-limiting embodiment of the present invention, which cross-sectional view can be taken along the axis of rotation X. As shown and as a non-limiting embodiment, the motor can be a permanent magnet synchronous motor and can mainly include a rotor 100 and a stator 200, etc.

[0040] An exemplary structure of the rotor 100 according to the present invention will be further described in detail below with reference to the accompanying drawings. The stator 200 can be arranged around the rotor 100 and is disposed radially outside the rotor 100. An air gap 300 can be provided between the rotor 100 and the stator 200.

[0041] As an example, the stator 200 can include a distributed winding that is wound and connected to an alternating current according to a predetermined rule to induce an alternating magnetic field, and the alternating magnetic field generates an electromagnetic torque on the rotor 100 to drive the rotor 100 to rotate.

[0042] The motor according to the present invention is a high-speed motor, and the rotational speed of its rotor 100 can exceed 40,000 revolutions per minute (rpm), for example, between 50,000 revolutions per minute and 150,000 revolutions per minute.

[0043] Figure 2 A schematic cross-sectional view of the rotor 100 for a motor according to a non-limiting embodiment of the present invention is shown, and this cross-sectional view can be taken along the rotation axis X.

[0044] As shown in the figure, the rotor 100 can generally have a substantially cylindrical shape and can mainly include components such as a magnetic core 10, a support device 20, and a sleeve 30.

[0045] According to the inventive concept of the present invention, the magnetic core 10 can be a segmented magnetic core and can include a plurality of magnets arranged at intervals along the rotation axis X of the rotor 100. In particular, the plurality of magnets can be a plurality of neodymium iron boron magnets.

[0046] The axial spacing between these magnets can be set very small, for example, it can be on the order of a few micrometers (for example, between 1 micrometer and 10 micrometers) or even a few nanometers (for example, between 1 nanometer and 10 nanometers), as long as the magnets do not form a continuous connection to reduce eddy current losses.

[0047] Preferably, adjacent magnets among the plurality of neodymium iron boron magnets of the magnetic core 10 can be fixed together via an insulating adhesive. The insulating adhesive can be, for example, a type that can be cured at high temperature such as epoxy resin.

[0048] As an example and as shown in the figure, each magnet in the magnetic core 10 can have a cylindrical shape, and the axial length of the magnetic core 10 formed by these magnets is between 30 mm and 80 mm, while the diameter of the magnetic core 10 is between 10 mm and 50 mm. It should be understood that the numerical ranges or intervals described herein include the values at the interval endpoints.

[0049] In addition, each magnet can have a central opening, such that after the plurality of neodymium iron boron magnets are axially aligned, the formed magnetic core 10 includes a central opening 10A. The central opening 10A can penetrate the magnetic core 10 along the rotation axis X, for example, fromFigure 2 extends through the magnetic core 10 from left to right.

[0050] It should be understood that according to the concept of the present invention, the magnetic core 10 formed as described above does not have additional structures such as silicon steel sheets.

[0051] Figure 3 Shows the relationship between the number of magnet segments of the rotor 100 according to the present invention and magnet loss and motor efficiency.

[0052] As shown in the figure, under the experimental conditions set by the inventor, as the number of magnet segments increases from 1 to 8, the magnet loss continuously decreases, and the motor efficiency also continuously increases. When the number of magnet segments exceeds 8, the motor efficiency will no longer increase. Therefore, preferably, the magnetic core 10 according to the present invention may include 3 - 10 magnets arranged at intervals along the rotation axis X, thereby achieving a balance between motor efficiency and magnet loss.

[0053] Continuing to refer to Figure 2 , the supporting device 20 can be arranged on both axial sides of the magnetic core 10 along the rotation axis X and support the magnetic core 10.

[0054] As an example, the supporting device 20 may include a first support member 21, an opposing second support member 22, and a pillar 23 extending between the first support member and the second support member. The first support member 21 and the second support member 22 can be respectively formed in the form of end shafts, and can each have a stepped cross - section so as to have two sections with different diameters along the rotation axis X.

[0055] In Figure 2 the illustrated embodiment, the first support member 21 may be provided with a first bearing portion 211 and a first mounting portion 212, while the second support member 22 may be provided with a second bearing portion 221 and a second mounting portion 222.

[0056] The first bearing portion 211 and the second bearing portion 221 can be used to support the rotor 100 and allow the rotor 100 to freely rotate around the rotation axis X.

[0057] For example, the first bearing portion 211 and the second bearing portion 221 can cooperate with bearings, such as air bearings or magnetic levitation bearings, etc. Additionally, the first support member 21 and the second support member 22 can be made of materials such as stainless steel or Inconel alloy, such as 316 stainless steel or Inconel alloy 718, etc. The outer surfaces of the first support member 21 and the second support member 22 can be pre - coated with chromium nitride or titanium nitride to reduce wear, especially when the motor 1000 starts.

[0058] In a preferred embodiment (not shown), the first support member 21 and the second support member 22 may also be directly connected to the impeller of the centrifuge, for example, via additional shafts extending from them and the like.

[0059] The first mounting portion 212 and the second mounting portion 222 may cooperate with the sleeve 30, thereby allowing the sleeve 30 to fix the magnetic core 10 and the support device 20 together.

[0060] As an example, the support pillar 23 may be integrally formed with the first support member 21, while the second support member 22 is provided with a support hole 22A, and the free end 23A of the support pillar 23 extends into the support hole 22A. Preferably, an interference fit may be formed between the free end 23A of the support pillar 23 and the support hole 22A.

[0061] In this way, the support pillar 23 may extend from the first support member 21 through the central opening 10A and be fixed to the second support member 22 to support the magnetic core 10 on the support device 20.

[0062] According to an embodiment of the present invention, the sleeve 30 may be made of a non-metallic material and disposed around the magnetic core 10 at the radially outer side of the magnetic core 10. As an example, a suitable non-metallic material may be selected, and the resistivity of the sleeve 30 is made to be to between.

[0063] It should be understood that the resistivity of the sleeve 30 as described herein is the resistivity measured at a temperature of 23°C ± 2°C and normal pressure (i.e., 1 standard atmosphere, 101.325 kPa), especially the resistivity measured along the axial direction of the sleeve 30.

[0064] Preferably, the sleeve 30 may be made of a carbon fiber material. Such a sleeve 30 can significantly increase the strength of the rotor 100 to adapt to high-speed rotation conditions, while further reducing eddy current losses, and reducing the air gap by reducing the thickness of the material used, thereby increasing the power density of the motor. Preferably, the wall thickness of the sleeve 30 may be less than 3 mm. For example, it may be between 1 mm and 1.5 mm, etc.

[0065] As a non-limiting example, the sleeve 30 may be pre-formed and the support device 20 and the magnetic core 10 may be press-fitted into the sleeve 30 to form an interference fit between the magnetic core 10 and the sleeve 30, without the need for additional bonding or welding supply. Alternatively, carbon fiber material may be woven around the magnetic core 10 and cured to form a structure fixed to the magnetic core 10.

[0066] In this way, the support device 20 and the magnetic core 10 are fixed together by the sleeve 30 and can rotate together around the rotation axis X.

[0067] Figure 4shows a schematic cross-sectional view of a motor of the prior art; while Figure 5 shows a schematic cross-sectional view of a motor 1000 according to a non-limiting embodiment of the present invention. Figure 4 and Figure 5 The cross-sectional plane of can be along a plane perpendicular to the rotation axis X.

[0068] As shown in the figure, with the same structure and arrangement of the stator 200, the rotor 100 of the motor 1000 according to the present invention has a smaller sleeve 30 thickness, and since the magnetic core 10 includes a plurality of segmented neodymium iron boron magnets and the sleeve 30 is made of carbon fiber, the generation of eddy currents can be significantly reduced, thereby reducing the size of the air gap 300 and increasing the power density of the motor.

[0069] As a non-limiting embodiment of the present invention, the present invention provides a method for manufacturing a rotor 100 for a motor, which may optionally include the following steps: Provide a magnetic core 10. Preferably, the magnetic core 10 may include a plurality of magnets, such as a plurality of neodymium iron boron.

[0070] Fix a plurality of neodymium iron boron magnets together along the axial direction, and arrange each of the plurality of neodymium iron boron magnets spaced apart along the rotation axis X of the rotor 100.

[0071] Optionally, adjacent magnets in the magnetic core 10 can be fixed together via an insulating adhesive, and the magnetic core 10 is placed in a heating device to cure the insulating adhesive.

[0072] Install the magnetic core 10 on a support device 20, and the support device 20 is arranged on both axial sides of the magnetic core 10 along the rotation axis X.

[0073] Arrange a sleeve 30 around the magnetic core 10, and the sleeve 30 can be made of a non-metallic material and arranged around the magnetic core 10 on the radial outside of the magnetic core 10. As described above, the material of the sleeve 30 can be selected, and the resistivity of the sleeve 30 is made to be between and .

[0074] Optionally, before assembling the magnetic core 10 into the sleeve 30, at least a part of the outer surfaces of the magnetic core 10 and the support device 20 can be ground, and then the magnetic core 10 and the support device 20 are press-fitted into the sleeve 30.

[0075] Alternatively, the sleeve 30 can be made of a carbon fiber material, and the carbon fiber material is woven around the magnetic core 10 and cured to form a sleeve 30 fixed to the magnetic core 10.

[0076] In this way, the sleeve 30 fixes the support device 20 and the magnetic core 10 together and can rotate together around the rotation axis X.

[0077] Optionally, the method may include the step of performing a dynamic balancing operation on the rotor 100; and optionally, the step of magnetizing the magnetic core 10.

[0078] It should be understood that the method steps described above are exemplary, and those skilled in the art can adjust the order of the method steps, add corresponding steps or delete relevant steps without departing from the scope of the present invention.

[0079] As used herein, the terms "left side" and "right side" indicating orientation or direction, and the terms "first", "second", etc. used to indicate order are merely for enabling those of ordinary skill in the art to better understand the concept of the present invention shown in the preferred embodiment form, rather than for limiting the present invention. Unless otherwise specified, all orders, orientations or directions are only for the purpose of distinguishing one element / component / structure from another element / component / structure, and do not represent any specific order, operation order, direction or orientation unless otherwise specified. For example, in an alternative embodiment, the "first support member" may be the "second support member".

[0080] As used herein, unless otherwise specified, the terms "substantially" and "about" are interpreted to mean plus or minus five percent of the numerical value or numerical range, or indicate a plus or minus five percent deviation in the shape and / or position.

[0081] In summary, the rotor 100 for an electric machine according to an embodiment of the present invention overcomes the disadvantages in the prior art and achieves the intended invention purpose.

[0082] Although the rotor for an electric machine of the present invention has been described above in conjunction with preferred embodiments, those of ordinary skill in the art should recognize that the above examples are only for illustration and cannot be used as a limitation to the present invention. Therefore, various modifications and variations can be made to the present invention within the spirit of the claims, and these modifications and variations will fall within the scope required by the claims of the present invention.

Claims

1. A rotor (100) for an electric motor, the rotor comprising: A magnetic core (10), the magnetic core comprising a plurality of neodymium iron boron magnets arranged at intervals along the rotation axis (X) of the rotor (100); Support means (20), the support means being provided on both axial sides of the magnetic core (10) along the rotation axis (X) and supporting the magnetic core (10); and A sleeve (30), which is made of a non-metallic material and is disposed radially outside the magnetic core (10) around the magnetic core (10), wherein the resistivity of the sleeve (30) is between and ​ Wherein, the support means (20) and the magnetic core (10) are fixed together by the sleeve (30) and are capable of rotating together about the rotation axis (X).

2. The rotor (100) for an electric machine according to claim 1, characterized in that, Adjacent magnets among the plurality of neodymium iron boron magnets of the magnetic core (10) are fixed together via an insulating adhesive.

3. The rotor (100) for an electric machine according to claim 1, characterized in that, The support means (20) comprises a first support member (21), an opposing second support member (22) and struts (23) extending between the first support member and the second support member, wherein, the magnetic core (10) comprises a central opening (10A), and the struts (23) extend through the central opening (10A) to support the magnetic core (10) on the support means (20).

4. The rotor (100) for an electric machine according to claim 3, characterized in that, The struts (23) are integrally formed with the first support member (21), and the second support member (22) is provided with support holes (22A), and the free ends (23A) of the struts (23) extend into the support holes (22A).

5. The rotor (100) for an electric machine according to claim 3, characterized in that, The outer surfaces of the first support member (21) and the second support member (22) are pre-coated with chromium nitride or titanium nitride.

6. The rotor (100) for an electric machine according to any one of claims 1-5, characterized in that, The sleeve (30) is made of a carbon fiber material.

7. The rotor (100) for an electric machine according to claim 6, characterized in that, The magnetic core (10) is press-fitted into the sleeve (30) or carbon fiber material is wound around the magnetic core (10) and cured to form an interference fit between the magnetic core (10) and the sleeve (30).

8. The rotor (100) for an electric machine according to any one of claims 1-5, characterized in that, Each magnet in the magnetic core (10) has a cylindrical shape, and the axial length of the magnetic core (10) is between 30 mm and 80 mm, while the diameter of the magnetic core (10) is between 10 mm and 50 mm.

9. The rotor (100) for an electric machine according to any one of claims 1-5, characterized in that, The magnetic core (10) comprises 3 to 10 magnets arranged at intervals along the rotation axis (X).

10. An electric motor (1000), the electric motor being a permanent magnet synchronous motor and comprising: A rotor (100) for an electric motor according to any one of claims 1-9; And A stator (200), the stator being arranged around the rotor (100) and provided radially outside the rotor (100), Wherein, the rotational speed of the rotor (100) is between 50,000 revolutions per minute and 150,000 revolutions per minute.

11. A method of manufacturing a rotor (100) for an electric motor, the method comprising the following steps: Providing a magnetic core (10), the magnetic core comprising a plurality of neodymium iron boron magnets; Fixing the plurality of neodymium iron boron magnets together in the axial direction and arranging each of the plurality of neodymium iron boron magnets at intervals along the rotation axis (X) of the rotor (100); Mounting the magnetic core (10) to a support means (20), the support means being provided on both axial sides of the magnetic core (10) along the rotation axis (X); A sleeve (30) is arranged around the magnetic core (10), the sleeve is made of a non-metallic material and is arranged around the magnetic core (10) at the radial outer side of the magnetic core (10), wherein the resistivity of the sleeve (30) is between and ; Wherein, the sleeve (30) fixes the supporting device (20) and the magnetic core (10) together and can rotate together around the rotation axis (X).

12. The method according to claim 11, wherein Adjacent magnets among the plurality of neodymium iron boron magnets are fixed together via an insulating adhesive, and the plurality of neodymium iron boron magnets are placed into a heating device to cure the insulating adhesive.

13. The method according to claim 11, characterized in that, Before assembling the magnetic core (10) into the sleeve (30), at least a part of the outer surfaces of the magnetic core (10) and the supporting device (20) is ground, and then the magnetic core (10) and the supporting device (20) are press-fitted into the sleeve (30).

14. The method according to claim 11, wherein The sleeve (30) is made of a carbon fiber material, and the carbon fiber material is woven around the magnetic core (10) and cured to form the sleeve (30) fixed to the magnetic core (10).

15. The method according to claim 11, wherein Further comprising: a step of performing a dynamic balancing operation on the rotor (100); and a step of magnetizing the magnetic core (10).

Images