Permanent Magnet Motors and Electric Drive Systems

Abstract

The present invention discloses a permanent magnet motor and electric drive system, in which the permanent magnet motor includes a stator and a rotor, the stator including stator core segments, the inner circular surface of which is provided with a plurality of axial stator teeth, a stator groove formed between adjacent two stator teeth, and auxiliary grooves formed at the tips of at least some of the stator teeth, and the permanent magnet motor has advantages such as low motor vibration noise and high NVH quality.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority from a Chinese patent application bearing application number 202211143555.2 and entitled "Permanent Magnet Motor and Electric Drive System," filed with the China Patent Office on September 20, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention is in the field of motor stators, and more particularly, permanent magnet motors and electric drive systems. [Background technology]

[0003] During operation, a permanent magnet synchronous motor generates electromagnetic torque through the interaction of the armature magnetic field and rotor magnetic field, which then converts electrical energy into mechanical energy to output power. The armature magnetic field is generated by the stator current, and the rotor magnetic field is provided by the rotor's permanent magnet. The armature magnetic field and rotor magnetic field combine to form an air-gap magnetic field within the motor's air gap. Due to factors such as magnetic saturation in the iron core, the air-gap magnetic field is not a standard sine wave but contains harmonic components. These harmonic components generate torque ripple and significant radial electromagnetic force waves at certain orders, which cause noise and vibration in the motor and further reduce the motor's NVH (Noise, Vibration, Harshness) quality. Summary of the Invention [Problem to be solved by the invention]

[0004] In response to the above problems, the present invention discloses a permanent magnet motor and an electric drive system to overcome or at least partially solve the above problems. [Means for solving the problem]

[0005] To achieve the above object, the present invention employs the following technical solutions.

[0006] In one aspect of the present invention, there is provided a permanent magnet motor, the permanent magnet motor including a stator and a rotor, The stator includes a stator core segment, and a plurality of axial stator teeth are provided on the inner circular surface of the stator core segment. A stator groove is formed between two adjacent stator teeth, and an auxiliary groove is opened at the tip of at least some of the stator teeth.

[0007] Furthermore, the rotor includes a plurality of rotor core segments that are offset from each other by a first preset angle, and the number of the stator core segments is plural, and each of the stator core segments and each of the rotor core segments are provided in correspondence with each other.

[0008] Furthermore, the positions and / or numbers of auxiliary grooves in the stator core segments corresponding to the different rotor core segments are different.

[0009] Furthermore, the shapes, positions and numbers of the auxiliary grooves in the stator core segments are the same, and the stator core segments are offset from each other by a second preset angle.

[0010] Furthermore, the auxiliary grooves in the stator core segments are arranged periodically.

[0011] Furthermore, several adjacent stator teeth that do not have the auxiliary groove at their tips are grouped together, and several adjacent stator teeth that have the auxiliary groove at their tips are grouped together, and the set of stator teeth that do not have the auxiliary groove at their tips and the set of stator teeth that have the auxiliary groove at their tips are arranged alternately and spaced apart.

[0012] Furthermore, the auxiliary grooves extend axially through the stator core segments.

[0013] Furthermore, the radial cross-sectional shape of the auxiliary groove is axially symmetrical, and the auxiliary groove is provided at a midpoint of the tip of the stator tooth so that the axis of symmetry of the axially symmetrical shape overlaps with the axis of symmetry of the stator tooth.

[0014] Furthermore, the radial cross section of the auxiliary groove is arc-shaped, U-shaped or V-shaped.

[0015] Another aspect of the present invention provides an electric drive system including the permanent magnet motor described above. [Effects of the Invention]

[0016] The advantages and beneficial effects of the present invention are as follows:

[0017] In the permanent magnet motor of the present invention, by opening auxiliary grooves at the tips of at least some of the stator teeth, it is possible to suppress to low levels both the torque ripple and radial electromagnetic force waves generated in both the rotor core segments and the stator core segments, and further reduce the torque ripple and radial electromagnetic force of the entire motor, thereby effectively suppressing the generation of vibration noise in the motor and improving the NVH quality of the motor. [Brief explanation of the drawings]

[0018] [Figure 1] 3 is a partial structural view of a stator core segment and a rotor core segment in one embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a radial cross-sectional view of three stator core segments after expansion in one embodiment of the present invention. [Figure 3] FIG. 3 is a partial structural view of one of the stator cores in FIG. 2. [Figure 4] FIG. 4 is a radial cross-sectional view of a stator core segment according to another embodiment of the present invention. [Figure 5] FIG. 10 is a radial cross-sectional view of a stator core segment according to still another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Various other benefits and advantages will become apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Furthermore, like reference numerals are used throughout the drawings to refer to like parts.

[0020] In order to make the objectives, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the described embodiments are only some embodiments of the present invention, and are not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without paying creative labor are included in the protection scope of the present invention.

[0021] Hereinafter, technical solutions according to various embodiments of the present invention will be described in detail with reference to the drawings.

[0022] In one embodiment of the present invention, a permanent magnet motor is disclosed, which includes a stator and a rotor.

[0023] Specifically, as shown in Figures 1 to 3, the stator includes a stator core segment 1, and a plurality of axial stator teeth 2 are provided on the inner circular surface of the stator core segment 1. The stator teeth 2 are for winding coil windings, and a stator groove 3 is formed between two adjacent stator teeth 2, allowing the coil winding to be accommodated in the stator groove 3. Auxiliary grooves 4 are formed at the tips of some of the stator teeth 2, and the auxiliary grooves 4 open toward the rotor. Of course, auxiliary grooves 4 may be formed at the tips of all of the stator teeth 2.

[0024] In summary, in the permanent magnet motor of this embodiment, by opening auxiliary grooves at the tips of at least some of the stator teeth and increasing the air gap between the stator and rotor, the radial electromagnetic force acting on the stator teeth is reduced, and the torque ripple and radial electromagnetic force waves generated in both the rotor core segments and the stator core segments are both kept to low levels. This further reduces the torque ripple and radial electromagnetic force of the entire motor, effectively suppressing motor vibration noise and improving the NVH quality of the motor. Furthermore, the structural design of the auxiliary grooves allows for a reduction in the mass of the stator without affecting its strength, further enabling a lightweight motor design.

[0025] In this embodiment, as shown in Figures 1 and 2, the rotor includes three rotor core segments 5, each offset by a first preset angle: first rotor core segment 5-1, second rotor core segment 5-2, and third rotor core segment 5-3. The rotor core segments 5 are designed to be offset by the first preset angle, reducing the cogging effect caused by the stator slots 3 and enabling smoother rotor rotation. Each of the three rotor core segments 5 has a through-slot 6 extending axially through its outer surface. The through-slot 6 design effectively disperses harmonic energy, optimizing the air-gap magnetic flux density waveform and further suppressing motor vibration and noise. The number of stator core segments 1 is also three: first stator core segment 1-1, second stator core segment 1-2, and third stator core segment 1-3. The three stator core segments 1 correspond to the three rotor core segments 5. The first preset angle is determined by simulating the motor. Of course, the number of rotor core segments 5 and stator core segments 1 may be other numbers.

[0026] In addition, the positions and / or numbers of auxiliary slots on the stator core segments corresponding to different rotor core segments are different. Since the rotor pole orientation angles on different rotor core segments are different, which causes differences in the air gap magnetic flux density waveforms synthesized on different rotor core segments, the positions and / or numbers of auxiliary slots need to be changed according to the rotor core segments corresponding to the stator core segments where they are located, thereby effectively reducing the harmonic content of the air gap magnetic flux density on each rotor core segment and achieving the purpose of suppressing motor vibration noise.

[0027] Furthermore, the shape, position, and number of auxiliary grooves in each stator core segment are consistent, and the stator core segments are offset from one another by a second preset angle. In this way, differences in the structure of each stator core segment can be maintained in terms of relative position, i.e., the relative positions of the auxiliary grooves in different stator core segments can be varied. The second preset angle is determined by motor simulation. The stator core segments in this embodiment can be manufactured using the same set of molds, further reducing the manufacturing costs of permanent magnet motors.

[0028] 1 to 3, the auxiliary grooves 4 penetrate the stator core segments 1 in the axial direction, and by adopting a structural design in which the auxiliary grooves 4 penetrate in the axial direction, not only is it easier to process the auxiliary grooves 4, but the shape and size of the auxiliary grooves 4 can also be easily controlled, resulting in better consistency between the auxiliary grooves 4 in each stator core segment 1. Of course, the auxiliary grooves 4 may be opened at the center of the tip of the stator tooth 2, and for example, the auxiliary groove may be a circular groove opened at the tip of the stator tooth.

[0029] In this embodiment, the auxiliary grooves in the stator core segments are periodically arranged, which improves the symmetry of the stator core segments and makes it easier to manufacture the auxiliary grooves in the stator core segments. Furthermore, because the coil windings in the stator core segments are periodically wound, the electromagnetic force generated by the coil windings is also periodic. Therefore, by periodically arranging the auxiliary grooves in the stator core segments, the motor vibration noise can be more effectively suppressed.

[0030] Furthermore, several adjacent stator teeth without auxiliary grooves at their tips are grouped together, and several adjacent stator teeth with auxiliary grooves at their tips are grouped together, and the set of stator teeth without auxiliary grooves at their tips and the set of stator teeth with auxiliary grooves at their tips are alternately spaced apart. Specifically, as shown in Figures 2 and 3, two adjacent stator teeth 2 without auxiliary grooves 4 at their tips are grouped together, and one stator tooth 2 with an auxiliary groove 4 at its tip is grouped together, and two stator teeth 2 without auxiliary grooves 4 at their tips and one stator tooth 2 with an auxiliary groove 4 at its tip are alternately spaced apart. In another embodiment, as shown in Figure 4, two adjacent stator teeth 2 without auxiliary grooves 4 at their tips may be grouped together, and four adjacent stator teeth 2 with auxiliary grooves 4 at their tips may be grouped together.

[0031] Of course, in other embodiments, the auxiliary grooves may be arranged with a more complex periodicity. For example, as shown in FIG. 5, every other stator tooth 2 without an auxiliary groove 4 at its tip is accompanied by one stator tooth 2 with an auxiliary groove 4 at its tip, and further, every third stator tooth 2 without an auxiliary groove 4 at its tip is accompanied by two stator teeth 2 with auxiliary grooves 4 at their tip.

[0032] In addition, the stator core segments are made by laminating stator blanks, which makes the manufacturing process simpler, and the stator blanks are press-formed, which makes the consistency of the stator core segments better.

[0033] In this embodiment, the radial cross section of the auxiliary groove is axially symmetrical, and the auxiliary groove is located at the middle of the tip of the stator tooth so that the axis of symmetry of the axially symmetrical shape overlaps with the axis of symmetry of the stator tooth, thereby ensuring the symmetry of the entire stator core segment and further improving the effect of suppressing motor vibration noise.

[0034] 1 to 3, the radial cross section of the auxiliary groove 4 is arc-shaped, and since the arc-shaped air resistance is small, it is possible to reduce the resistance generated when the motor starts. Of course, the radial cross section of the auxiliary groove 4 may be U-shaped, V-shaped, or another shape.

[0035] Another embodiment of the present invention discloses an electric drive system including the permanent magnet motor of the above embodiment, which has advantages such as low vibration noise and high NVH quality.

[0036] The above-mentioned are merely specific embodiments of the present invention, and those skilled in the art can make other improvements or modifications based on the above teachings of the present invention. Those skilled in the art should understand that the above specific descriptions are for better understanding the purpose of the present invention, and the protection scope of the present invention is subject to the protection scope of the claims. [Explanation of symbols]

[0037] 1 stator core segment, 2 stator tooth, 3 stator groove, 4 auxiliary groove, 5 rotor core segment, 6 through groove

Claims

1. A permanent magnet motor, the permanent magnet motor including a stator and a rotor; a stator core segment having an inner circular surface on which a plurality of axial stator teeth are provided, a stator groove being formed between two adjacent stator teeth, and an auxiliary groove being opened at the tip of at least some of the stator teeth.

2. 2. The permanent magnet motor according to claim 1, wherein the rotor includes a plurality of rotor core segments that are offset from each other by a first preset angle, the number of the stator core segments is plural, and the stator core segments and the rotor core segments are provided corresponding to each other.

3. 3. The permanent magnet motor according to claim 2, wherein the positions and / or numbers of auxiliary grooves in the stator core segments corresponding to the different rotor core segments are different.

4. 3. The permanent magnet motor according to claim 2, wherein the auxiliary grooves in each of the stator core segments are the same in shape, position, and number, and the stator core segments are offset from each other by a second preset angle.

5. 2. The permanent magnet motor according to claim 1, wherein the auxiliary grooves in the stator core segments are arranged periodically.

6. 6. The permanent magnet motor according to claim 5, wherein several adjacent stator teeth that do not have the auxiliary groove at their tips are grouped together, and several adjacent stator teeth that have the auxiliary groove at their tips are grouped together, and the set of stator teeth that do not have the auxiliary groove at their tips and the set of stator teeth that have the auxiliary groove at their tips are arranged alternately and spaced apart.

7. 7. The permanent magnet motor according to claim 1, wherein the auxiliary grooves penetrate the stator core segments in the axial direction.

8. The permanent magnet motor according to any one of claims 1 to 6, characterized in that the radial cross-sectional shape of the auxiliary groove is axially symmetrical, and the auxiliary groove is provided at an intermediate position of the tip of the stator tooth so that the axis of symmetry of the axially symmetrical shape overlaps with the axis of symmetry of the stator tooth.

9. 9. The permanent magnet motor according to claim 8, wherein the radial cross section of the auxiliary groove is arc-shaped, U-shaped, or V-shaped.

10. An electric drive system, characterized in that the electric drive system includes a permanent magnet motor according to any one of claims 1 to 9.

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