Electric motor rotor and electric motor

Abstract

This invention relates to an electric motor rotor and an electric motor. The electric motor rotor has an iron core on which multiple magnetic pole regions are arranged uniformly along the circumference of the iron core. Each magnetic pole region includes a first pole pair and a second pole pair. The first pole pair is closer to the outer circumference of the iron core than the second pole pair. The first and second pole pairs are symmetrically arranged about the central axis of their respective magnetic pole regions and each has two end magnets. Identical magnetic pole regions are symmetrically arranged along the diameter of the iron core. One or more magnetic pole regions differ in angle from adjacent magnetic pole regions in relation to the two end magnets of the second pole pair. The electric motor rotor according to this application can reduce higher harmonics of radial electromagnetic force through the asymmetry of adjacent magnetic pole regions, thereby improving motor vibration and noise problems.

Description

Technical Field

[0001] The present invention relates to an electric motor rotor and an electric motor having such an electric motor rotor. Background Technology

[0002] In both pure electric and hybrid drive systems, the drive motor plays a crucial role in the quality of the drive system and the driving range. Permanent magnet synchronous motors, especially built-in permanent magnet synchronous motors, are often used as the main drive motor due to their wide speed range, large reluctance torque, high low-speed efficiency, and good weak magnetic properties.

[0003] However, built-in permanent magnet synchronous motors generate tangential torque fluctuations during operation. Additionally, the radial electromagnetic force acting on the stator core may produce high-order harmonics, ultimately causing vibration and noise in the vehicle, i.e., NVH (Noise, Vibration, and Harshness) issues. The torque fluctuations mentioned here can also be caused by imperfections in the motor's own structure. For example, due to space and cost constraints in automotive installations, built-in permanent magnet motors are typically designed to be compact and have high air gap magnetic flux density. Summary of the Invention

[0004] One objective of one aspect of this invention is to provide an improved topology for an electric motor, particularly an electric motor rotor, which can improve motor vibration and noise problems.

[0005] According to one aspect of the invention, an electric motor rotor has an iron core on which a plurality of magnetic pole regions are arranged uniformly along the circumference of the iron core. Each magnetic pole region includes a first magnetic pole pair and a second magnetic pole pair. The first magnetic pole pair is closer to the outer circumference of the iron core than the second magnetic pole pair. The first and second magnetic pole pairs are arranged symmetrically about the central axis of their respective magnetic pole regions and each has two end magnets. Identical magnetic pole regions are arranged symmetrically in the diametrical direction of the iron core. One or more magnetic pole regions differ from adjacent magnetic pole regions in terms of the angle between the two end magnets of the second magnetic pole pair.

[0006] According to one aspect of the invention, an electric motor rotor is provided in which one or more magnetic pole regions differ from adjacent magnetic pole regions in terms of the pole arc coefficient of the second magnetic pole pair.

[0007] According to one aspect of the invention, an electric motor rotor has one or more auxiliary slots provided in a region surrounded by the outer circumference of the first magnetic pole pair and the iron core, the auxiliary slots being arranged symmetrically about the central axis of the associated magnetic pole region.

[0008] According to one aspect of the present invention, an electric motor rotor has auxiliary slots of different shapes provided in adjacent magnetic pole regions.

[0009] According to one aspect of the present invention, an electric motor rotor has a different number of auxiliary slots in adjacent magnetic pole regions.

[0010] According to one aspect of the invention, an intermediate magnet is arranged between the two end magnets in the motor rotor.

[0011] According to one aspect of the present invention, a motor rotor is provided with weight-reducing holes in each magnetic pole region to reduce the rotational inertia of the motor rotor.

[0012] According to one aspect of the invention, the first and second pole pairs of the motor rotor are made of neodymium iron boron, ferrite, or samarium cobalt materials.

[0013] According to one aspect of the invention, the motor rotor has an iron core formed by pressing multiple layers of laminations, with the magnetic pole regions arranged on each lamination.

[0014] According to this application, the motor rotor can reduce higher harmonics of radial electromagnetic force through the asymmetry of adjacent magnetic pole regions, thereby improving motor vibration and noise problems.

[0015] According to another aspect of the invention, an electric motor having a stator and such an electric rotor is proposed. Attached Figure Description

[0016] Referring to the accompanying drawings, the above and other features of the present invention will become apparent, wherein:

[0017] Figure 1 A schematic diagram of an electric motor rotor according to the present invention is shown;

[0018] Figure 2 Showing according to Figure 1 A portion of the motor rotor. Detailed Implementation

[0019] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0020] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the structures shown in the accompanying drawings. These are relative concepts and may therefore vary depending on their location and usage. Therefore, these or other directional terms should not be interpreted as restrictive. Furthermore, the terms "first," "second," "third," and similar expressions are used for descriptive and distinguishing purposes only and should not be construed as indicating or implying the relative importance of the corresponding components.

[0021] Figure 1 A schematic diagram of an electric motor rotor is shown, in which other accessories of the motor rotor are not shown for clarity. The motor rotor has an iron core, which can be formed by pressing multiple layers of laminations, each lamination having the same structure. A through hole is provided in the center of the iron core, and multiple magnetic pole regions 1 are provided on the iron core, evenly distributed along its circumference. Each magnetic pole region is constructed in a fan shape, for example... Figure 1 The system has eight magnetic pole regions, each occupying a central angle of 45° relative to the center of the iron core. In other words, when there are N magnetic pole regions, the central angle of each magnetic pole region is 360° / N. For clarity, only two adjacent magnetic pole regions are labeled "1" in the attached figures. Each magnetic pole region contains multiple magnetic pole pairs, which are arranged symmetrically about the central axis of their respective pole region (which intersects the center of the iron core and the pole region is symmetrical about its central axis). For example, two magnetic pole pairs can be provided, as will be described in detail below. For example, more than two magnetic pole pairs can also be provided, i.e., an intermediate magnetic pole pair can also be provided.

[0022] First, it should be noted that the concept of "pole pair" used here is not limited to being composed of two parts, but can be composed of more than two components.

[0023] Below, in conjunction with Figure 1 and 2 The embodiments shown are explained in detail below. A first magnetic pole pair 11 and a second magnetic pole pair 12 are provided in each magnetic pole region 1, wherein the first magnetic pole pair 11 is closer to the outer circumference of the iron core than the second magnetic pole pair 12. Each magnetic pole pair includes a plurality of separate magnets (which may also be referred to as permanent magnets) embedded inside the iron core. Specifically, the first magnetic pole pair 11 has a plurality of magnets 111 and the second magnetic pole pair 12 has a plurality of magnets 121. In the embodiment shown in the figures, the first and second magnetic pole pairs 11 and 12 each have two magnets, which may also be referred to as end magnets.

[0024] The magnets 111 of the first pole pair 11 are accommodated and fixed in magnetic slots formed on the iron core. These slots are constructed to be relatively long relative to the magnets, and thus have a first slot 112 and a second slot 113 at each end. These first and second slots are not for accommodating the magnets. The first slot 112 is closer to the outer circumference of the iron core and forms an external magnetic bridge therewith. In contrast, the second slot 113 is located between magnets 111 belonging to the same pole pair, and together with the adjacent second slot 113, forms a force-bearing magnetic bridge. Furthermore, the width of the magnetic slot at the section used to accommodate the magnet is greater than at its first and second slots, thus itself acting as a stop to prevent movement of the magnet within the slot. The description of the first pole pair also applies to the second pole pair or other separately arranged intermediate pole pairs.

[0025] It should be noted that the terms "first slot" and "second slot" are based solely on their function and relative position, and are not limited in number.

[0026] According to the present invention, the vibration and noise problems of the motor are mitigated by the asymmetric topology of the motor rotor. This can be achieved by arranging adjacent magnetic pole regions differently, but it should be noted that the same magnetic pole regions must be arranged along the diameter of the iron core, that is, the magnetic pole regions opposite each other have the same arrangement or structure in order to ensure the rotational balance of the rotor.

[0027] The asymmetry can be achieved by having the angles formed by the two end magnets of each pole pair differ in adjacent pole regions. For example, in one pole region, the angle between the two end magnets 121 of the second pole pair 12 is 120°, while in an adjacent pole region, the angle is 117°. This improves the adjustability of the air gap magnetic density waveform and facilitates a balance between torque fluctuations and the sinusoidal nature of the back electromotive force. Alternatively, the difference between adjacent pole regions can also be achieved by having the second pole pairs in adjacent pole regions have different pole arc coefficients. In this way, the asymmetry of the second pole pairs in adjacent pole regions disperses the harmonics of the radial force and effectively reduces the major orders that cause motor vibration noise.

[0028] It should be noted here that the description of the second magnetic pole pair for the purpose of constructing different adjacent magnetic pole regions also applies to the first magnetic pole pair or other arranged intermediate magnetic pole pairs.

[0029] Optionally, in each magnetic pole region, one or more auxiliary slots 13 are arranged in the region between the first magnetic pole pair and the outer circumference of the iron core. These slots are symmetrically arranged about the central axis of the assigned magnetic pole region to ensure the rotational balance of the motor rotor. Here, the auxiliary slots 13 compress the magnetic circuits of the motor's D and Q axes, thereby changing the motor's torque characteristics to reduce torque ripple.

[0030] Optionally, the differences between adjacent magnetic pole regions mentioned above can be achieved by providing different auxiliary slots, such as auxiliary slots of different shapes and numbers. As shown in the accompanying drawings, one magnetic pole region has only one auxiliary slot 13, while the adjacent magnetic pole region has two auxiliary slots 13. The auxiliary slots 13 can be configured to have a circular, rectangular, or polygonal cross-section, for example. Here, the number and shape of the auxiliary slots can be changed as needed.

[0031] Optionally, in each pair of magnetic poles, there is also an intermediate magnet (not shown) between the two end magnets. This intermediate magnet can be oriented, for example, perpendicular to the central axis of the assigned magnetic pole region, and the magnetic slots belonging to the intermediate magnet form a force-bearing magnetic bridge on both sides with the adjacent end magnets or other intermediate magnets.

[0032] Furthermore, in order to reduce the rotational inertia of the motor rotor, weight-reducing holes 14 with the same arrangement are provided in each magnetic pole region. These weight-reducing holes can have a polygonal or circular shape, and are preferably rounded.

[0033] Optionally, the first and second magnetic pole pairs and, if possible, intermediate magnetic pole pairs can be made of neodymium iron boron, ferrite, or samarium cobalt materials.

[0034] In addition, this application also relates to a motor having such a motor rotor, which also has a stator that works in conjunction with the rotor, and which can have the advantages described above, which will not be repeated here.

[0035] It should be understood that all the above preferred embodiments are exemplary and not restrictive, and various modifications or variations made by those skilled in the art to the specific embodiments described above under the concept of the present invention should be within the legal protection scope of the present invention.

Claims

1. An electric motor rotor having an iron core on which multiple magnetic pole regions are arranged uniformly along the circumference of the iron core. Each magnetic pole region includes a first pole pair and a second pole pair. The first pole pair is closer to the outer circumference of the iron core than the second pole pair. The first and second pole pairs are arranged symmetrically about the central axis of their respective magnetic pole regions and each has two end magnets. The same magnetic pole regions are arranged symmetrically along the diameter of the iron core, wherein one or more magnetic pole regions differ from adjacent magnetic pole regions in terms of the angle between the two end magnets of the second magnetic pole pair.

2. The motor rotor according to claim 1, characterized in that, One or more of the magnetic pole regions differ from the adjacent magnetic pole regions in terms of the polar arc coefficient of the second magnetic pole pair.

3. The motor rotor according to claim 1, characterized in that, One or more auxiliary slots are provided in the area surrounded by the outer circumference of the first magnetic pole pair and the iron core, and the auxiliary slots are arranged symmetrically about the central axis of the magnetic pole region to which they belong.

4. The motor rotor according to claim 3, characterized in that, Different shaped auxiliary slots are set in adjacent magnetic pole regions.

5. The motor rotor according to claim 3, characterized in that, Different numbers of auxiliary slots are set in adjacent magnetic pole regions.

6. The motor rotor according to claim 1, characterized in that, An intermediate magnet is arranged between the two end magnets.

7. The motor rotor according to claim 1, characterized in that, Weight reduction holes are provided in each magnetic pole region to reduce the rotational inertia of the motor rotor.

8. The motor rotor according to claim 1, characterized in that, The first magnetic pole pair and the second magnetic pole pair are made of neodymium iron boron, ferrite, or samarium cobalt materials.

9. The motor rotor according to any one of claims 1 to 8, characterized in that, The iron core is formed by pressing multiple layers of laminations, with the magnetic pole region arranged on each lamination.

10. An electric motor, characterized in that, It has a stator and an electric motor rotor according to any one of claims 1 to 9.

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