Asymmetric skewed rotor

Abstract

An asymmetrically skewed rotor and an electric motor incorporating the rotor. The rotor is configured to rotate within a stator positioned around a portion of the rotor. The stator and rotor are aligned along a centerline (x). Each rotor includes an asymmetrical feature such that, during operation, dynamic balance occurs when the asymmetrical features on each rotor are aligned relative to each other perpendicular to the centerline (x), and static balance occurs when the asymmetrical features on each rotor are aligned relative to each other parallel to the centerline (x).

Description

Technical Field

[0001] The present disclosure generally relates to an asymmetric skewed rotor configured for use in an electric motor, such as a permanent magnet synchronous motor (PMSM). Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Due to developments in power electronics (e.g., improvements in inverters and the use of vector control methods), the use of electric motors in many applications (e.g., high-speed transportation) has transitioned from direct current (DC) drives to alternating current (AC) drives. Compared to DC drives, AC drives offer higher reliability, high efficiency, superior power density, and lower maintenance requirements. AC drives are typically associated with induction motors (IM) and permanent magnet synchronous motors (PMSM). The current trend appears to be shifting towards the preferential use of PMSM technology based on its potential for high efficiency and power density, although this technology is also associated with higher manufacturing and material costs.

[0004] A PMSM is an AC synchronous motor whose excitation is provided by permanent magnets. A PMSM may include a magnet arrangement located on or within the rotor surface, with the magnets exhibiting either radial or tangential magnetization. The performance of a PMSM with surface mounted magnets is similar to that of a synchronous motor with a cylindrical rotor, where torque is generated entirely by the interaction between the rotor flux and the stator current. While PMSMs offer many advantages, the technology also exhibits a number of disadvantages, such as the constant flux provided by the magnets and the high cost associated with rare earth magnets. Furthermore, rotors associated with PMSMs are known to exhibit cogging torque, as well as generate harmonics and vibrations during operation, necessitating the use of rotor skew to reduce harmonics and axial counterweights to reduce vibrations, which increases the size (e.g., length using end-mounted counterweights) and cost associated with the motor assembly. Summary of the Invention

[0005] The present disclosure generally provides a plurality of asymmetric skewed rotors for an electric motor, and an electric motor formed therefrom. The rotor is configured to rotate within a stator positioned around a portion of the rotor, wherein the stator and rotor are aligned along a centerline (x). Each rotor includes asymmetric features such that, during operation, dynamic balance is achieved when the asymmetric features on each rotor are aligned relative to each other perpendicular to the centerline (x), and static balance is achieved when the asymmetric features on each rotor are aligned relative to each other parallel to the centerline (x).

[0006] According to another aspect of the present disclosure, an asymmetrically skewed rotor is incorporated into an electric motor, including but not limited to a permanent magnet synchronous motor (PMSM).The rotor, representing a rotating machine, is at least partially surrounded by a stator.

[0007] Further areas of applicability will become apparent from the description provided herein.It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a better understanding of the present disclosure, various forms of the present disclosure will now be described by way of example with reference to the accompanying drawings, in which:

[0009] Figure 1A is a schematic diagram of the conventional stator and rotor in a PMSM viewed along the centerline (x);

[0010] Figure 1B is a schematic diagram of another conventional stator and rotor in a PMSM viewed along the centerline (x);

[0011] Figure 2A is a schematic diagram of a stator and an asymmetrically skewed rotor showing a dynamic balance according to the teachings of the present disclosure, viewed along a centerline (x);

[0012] Figure 2B This further demonstrates dynamic balance. Figure 2A A perspective view of an asymmetrically skewed rotor in FIG;

[0013] Figure 3A is a schematic diagram of a stator and an asymmetrically skewed rotor showing a static balance according to the teachings of the present disclosure, viewed along a centerline (x); and

[0014] Figure 3B This further demonstrates static equilibrium. Figure 3A A perspective view of an asymmetric skewed rotor in Figure 1.

[0015] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. It should be understood that throughout the description, corresponding reference numerals indicate like or corresponding parts and features. DETAILED DESCRIPTION

[0016] Various embodiments described herein focus on an asymmetric skewed rotor configured for use as a rotating mechanism within an electric motor. The following description is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or uses. For example, throughout this disclosure, asymmetric rotor elements made and used according to the teachings contained herein are described in conjunction with a permanent magnet synchronous motor (PMSM) to more fully illustrate their construction and use. It is within the scope of this disclosure to incorporate and use such rotor elements in any machine, industrial equipment, or other device requiring an electric motor (such as, but not limited to, a PMSM, a servo motor, etc.).

[0017] The present disclosure generally provides an asymmetric skewed rotor for use as part of a rotating mechanism in an electric motor, and an electric motor incorporating such a rotor. Balancing the rotating mechanism of a motor is essential to achieve noise, vibration, and performance targets. Using an asymmetric skewed rotor as described above and further defined herein achieves these goals without adding external counterweights to the design, thereby reducing overall cost and axial packaging space. Auxiliary counterweights can still be used if desired, but their size can be minimized.

[0018] refer to Figure 1A and Figure 1B Conventional electric motors 1a, 1b, including but not limited to alternating current (AC) electric motors, typically include a rotor 2 and a stator 3. When the AC electric motor is a permanent magnet synchronous motor (PMSM), the rotor includes a plurality of permanent magnets 4 and the stator includes coil windings 5. PMSM motors can be divided into two main types, surface permanent magnet motors or interior permanent magnet motors (IPM). More specifically, the permanent magnets 4 can be fixed to the surface of the rotor 2 (e.g., Figure 1A as shown) or position them inside the rotor 2 (as Figure 1B Both motor types generate magnetic flux via permanent magnets fixed to or within the rotor. Surface mounting of the magnets can weaken the assembly's mechanical strength, limiting the safe mechanical speed at which the motor can operate. Embedding the permanent magnets 4 within the rotor 2, on the other hand, makes the motor mechanically very robust and suitable for operation at very high speeds.

[0019] Still refer to Figure 1A and Figure 1B The magnets 4 can be placed in a variety of locations, however, so placed as to produce a symmetrical pattern around the center line (x). Each magnet can be inserted as a large block, or can be staggered as they approach the core. Another approach is to embed them in a spoke pattern. The number of magnets 4 can range from 4 to about 20, or 12 or less. Alternatively, the number of magnets 4 is represented by an even number, such as, but not limited to, four (see Figure 1A ), six (see Figure 1B ), eight, ten, or twelve. The permanent magnets may include, but are not limited to, neodymium-iron-boron (Nd-Fe-B), samarium-cobalt (Sm-Co), aluminum-nickel-cobalt (alnico), or ferrites (barium and strontium).

[0020] The stator windings 5 ​​in the stator 3 of a permanent magnet synchronous motor (PMSM) 1a, 1b generate a rotating magnetic field that repels the magnetic field exhibited by the permanent magnets 4, thereby causing the rotor 2 to rotate. The efficiency of the PMSM relative to other motors (such as induction motors) is mainly due to the fact that the rotor magnets create an independent and permanent magnetic field, because no additional current needs to be induced to create the rotor magnetic field.

[0021] Now refer to Figure 2A 、 Figure 2B 、 Figure 3A and Figure 3B According to a permanent magnet synchronous motor (PMSM) 1c of one aspect of the present disclosure, a plurality of rotors 2 are configured to rotate within a stator 3 positioned around a portion of the rotor 2, with the stator 3 and the rotor 2 aligned along a centerline (x). Each rotor 2 includes an asymmetric feature 7, such that during operation, when the asymmetric features 7 on each rotor 2 are aligned relative to each other perpendicular to the centerline (x), dynamic balance (e.g., Figure 2A and Figure 2B As shown), when the asymmetric features 7 on each rotor 2 are aligned relative to each other parallel to the centerline (x), static balance (as shown) is produced. Figure 3A and Figure 3B shown).

[0022] The asymmetric skewed rotor 2 may comprise a laminated stamping. In addition to the asymmetric features 7, the laminated stamping may also comprise one or more symmetric features 8. Any type of material known for laminated stampings of motor assemblies may be used, including but not limited to cobalt-iron alloys, nickel-iron alloys, silicon or electrical steel, iron-boron-silicon alloys, and laminated steel. Still referring to Figure 2A 、 Figure 2B 、 Figure 3A and Figure 3B , the symmetrical features 8 and the asymmetrical features 7 can be apertures 6 formed in the rotor 2. The shapes of these apertures 6 can include any type of geometric shape. Examples of possible geometric shapes include, but are not limited to, a circle, an ellipse, a square, a rectangle, a triangle, a rhombus, a trapezoid, a hexagon, an octagon, or a parallelogram. Alternatively, the shape of the aperture 6 is a circle, a rectangle, a rhombus, a triangle, or a trapezoid. Any shape of aperture 6 can be used, as long as such shape is optimized so as not to affect the magnetic circuit of the rotor. The aperture 6 of the asymmetrical feature 7 can be configured as a portion of the aperture 6 of the symmetrical feature 8. For example, if the aperture 6 of the symmetrical feature 8 is a circle, the aperture 6 of the asymmetrical feature 7 can be a semicircle.

[0023] The number of holes 6 in the rotor 2 may be 4 to about 20, or 12 or less. Alternatively, the number of holes 6 is represented by an even number, such as, but not limited to, four, six (see Figure 2A 、 Figure 2B 、 Figure 3A 、 Figure 3B ), eight, ten, or twelve. The number of openings 6 can reflect the number of magnets or poles incorporated into the rotor, thereby reducing the overall mass of the rotor. Other features of the rotor, such as the type and number of permanent magnets, the material composition of the laminated stampings, and the design and configuration of the stator and stator windings, can be similar or identical to those in conventional motors.

[0024] According to another aspect of the present disclosure, a rotor as described above and further defined herein is used to form an electric motor, such as a PMSM. The electric motor includes a stator positioned to at least partially surround the rotor. The stator and rotor are positioned so that they are aligned along a centerline (x).

[0025] In this specification, embodiments have been described in a manner that makes the written description clear and concise, but it is intended and should be understood that the embodiments can be combined or separated in various ways without departing from the present invention. For example, it should be understood that all preferred features described herein are applicable to all aspects of the invention described herein.

[0026] The foregoing description of the various forms of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications and variations are possible in light of the above teachings. The forms discussed have been selected and described to provide the best illustration of the principles of the invention and its practical application, thereby enabling one of ordinary skill in the art to utilize the invention in various forms and with various modifications suitable for a particular use. All such modifications and variations, when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled, are within the scope of the present invention as determined by the appended claims.

Claims

1. A motor having a rotating mechanism, the rotating mechanism comprising a stator surrounding a portion of a plurality of rotors, the stator and rotors being aligned along a centerline (x); in, The plurality of rotors are a plurality of asymmetrically skewed rotors, each rotor including an asymmetrical feature such that during operation, dynamic balance occurs when the asymmetrical features on each rotor are aligned relative to each other perpendicular to a centerline (x), and static balance occurs when the asymmetrical features on each rotor are aligned relative to each other parallel to the centerline (x), wherein each rotor comprises a laminated stamping comprising one or more symmetrical features in addition to said asymmetrical features, wherein the one or more symmetrical and asymmetrical features are apertures formed in the rotor, The shape of the orifice of the asymmetric feature is different from the shape of the orifice of the symmetric feature.

2. The motor according to claim 1, wherein The motor is an AC motor.

3. The motor according to claim 2, wherein The AC motor is a permanent magnet synchronous motor.

4. The motor according to claim 3, wherein The permanent magnet synchronous motor includes a plurality of permanent magnets disposed on a surface of the rotor or located inside a body of the rotor.

5. The motor according to claim 4, wherein Each of the permanent magnets is independently selected to be neodymium-iron-boron (Nd-Fe-B), samarium-cobalt (Sm-Co), aluminum-nickel-cobalt (alnico), or ferrite.

6. The motor according to claim 1, wherein The shape of the orifice is circular, elliptical, square, rectangular, triangular, rhombus, trapezoidal, hexagonal, octagonal or parallelogram.

7. The motor according to claim 1, wherein The aperture of the asymmetrical feature appears as a portion of the aperture of the symmetrical feature.

8. A plurality of rotors for a motor, the rotors being configured to rotate within a stator positioned around a portion of the rotor, the stator and rotor being aligned along a centerline (x); in, The plurality of rotors are a plurality of asymmetrically skewed rotors, each rotor including an asymmetrical feature such that during operation, dynamic balance occurs when the asymmetrical features on each rotor are aligned relative to each other perpendicular to a centerline (x), and static balance occurs when the asymmetrical features on each rotor are aligned relative to each other parallel to the centerline (x), wherein each rotor comprises a laminated stamping comprising one or more symmetrical features in addition to said asymmetrical features, wherein the one or more symmetrical and asymmetrical features are apertures formed in the rotor, The shape of the orifice of the asymmetric feature is different from the shape of the orifice of the symmetric feature.

9. The rotor according to claim 8, wherein: The motor is an AC motor.

10. The rotor according to claim 9, wherein: The AC motor is a permanent magnet synchronous motor.

11. The rotor according to claim 10, wherein: The permanent magnet synchronous motor includes a plurality of permanent magnets disposed on a surface of the rotor or located inside a body of the rotor.

12. The rotor according to claim 11, wherein: Each of the permanent magnets is independently selected to be neodymium-iron-boron (Nd-Fe-B), samarium-cobalt (Sm-Co), aluminum-nickel-cobalt (alnico), or ferrite.

13. The rotor according to claim 8, wherein The shape of the orifice is circular, elliptical, square, rectangular, triangular, rhombus, trapezoidal, hexagonal, octagonal or parallelogram.

14. The rotor according to claim 8, wherein The aperture of the asymmetrical feature appears as a portion of the aperture of the symmetrical feature.

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