Rotor structure of permanent magnet motor

Abstract

The invention relates to a permanent magnet motor rotor structure, and relates to the technical field of permanent magnet motors, the permanent magnet motor rotor structure comprises a rotor iron core, the rotor iron core is provided with placing grooves, the placing grooves comprise a first groove and second grooves, the two ends of the first groove are connected with the second grooves, the second grooves are obliquely arranged, and the second grooves at the two ends of the first groove are symmetrically arranged. A third groove is formed between every two adjacent first grooves in the circumferential direction, and magnetic steel of the same specification is arranged in the first grooves and the third grooves. The invention has the advantages of improving the waveform of the air-gap magnetic field, reducing the harmonic content of the air-gap magnetic field and improving the torque ripple, vibration and noise of the motor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of permanent magnet motors, in particular to a permanent magnet motor rotor structure. BACKGROUND

[0002] With the development of power electronics technology, permanent magnet synchronous motors have been widely used in the market, but due to the fact that rare earth materials are non-renewable resources, neodymium iron boron is expensive, in order to replace rare earth permanent magnet motors, permanent magnet auxiliary reluctance synchronous motors using ferrite permanent magnets have developed rapidly in recent years, but the existing permanent magnet auxiliary reluctance synchronous motors on the market basically adopt a multi-layer radial magnetic steel arrangement structure, especially for small power permanent magnet auxiliary reluctance synchronous motors, the rotor core space is limited, in order to maximize the magnetic flux, the magnetic steel shape is often designed as a circular arc, although the power density problem of the permanent magnet auxiliary reluctance synchronous motor is solved, the air gap magnetic field distribution of this kind of rotor topology is still close to a square wave, and the motor's tooth slot torque, torque ripple and noise cannot be effectively controlled. SUMMARY

[0003] In view of the deficiencies in the prior art, one of the purposes of the present application is to provide a permanent magnet motor rotor structure which has the advantages of being able to improve the air gap magnetic field waveform, reduce the air gap magnetic field harmonic content, and improve the motor torque ripple, vibration and noise.

[0004] The above-mentioned purpose of the present application is realized by the following technical scheme: A permanent magnet motor rotor structure, comprising a rotor core, wherein the rotor core is provided with a placement slot, the placement slot comprises slot one and slot two, both ends of the slot one are connected with the slot two, the slot two is inclinedly arranged, the slot two at both ends of the slot one is symmetrically arranged, a slot three is further arranged between the circumferentially adjacent slot ones, and the same specification magnetic steel is arranged in the slot one and the slot three.

[0005] In a preferred example, the placement slot can be further configured to be arranged in multiple layers in the direction towards the center of the circle.

[0006] In a preferred example, the outer end of the slot three and the outer end of the slot two are provided with a magnetic isolation bridge.

[0007] In a preferred example, the placement slot has two layers, the width of the magnetic steel is W, the distance between the outer layer slot two and the inner layer slot two is A, 0.3W≤A≤0.8W, the distance between the inner layer slot two and the slot three is B, and the size relationship between B and W is 0.3W≤B≤W.

[0008] The application can be further configured in a preferred example that: the adjacent air slots between the third slots are arc-shaped, the air slots take the axis as the center, the outer edge radius of the air slots is R2, the distance between the bottom of the magnetic steel in the third slot and the center is R1, and 0.1L≤R2-R1≤0.2L.

[0009] The application can be further configured in a preferred example that: the distance between the magnetic steel in the outer layer of the first slot and the outer circle of the rotor is H3, the radial distance between the magnetic steel in the middle of the two layers of the first slot is H2, and the distance between the magnetic steel in the inner layer of the first slot and the air slot is H1; the relationship between H1, H2 and H3 is 1≤H1:H2≤1.2 and 1≤H2:H3≤1.2; the size relationship between H3 and W is 0.5W≤H3≤W.

[0010] The application can be further configured in a preferred example that: the rotation center is O point, the angle formed by the outer vertex of the magnetic steel in the outer layer of the first slot and the line is α, and the angle formed by the inner vertex of the magnetic steel in the inner layer of the first slot and the line is β, 78°≤α*p≤90° and 120°≤β*p≤140°.

[0011] The application can be further configured in a preferred example that: the specifications of the magnetic steels in the first slot and the third slot are the same. The application has the following advantages: The rotor topology structure arranged by the magnetic steels (radial magnetic steels) in the first slot and the magnetic steels (tangential magnetic steels) in the third slot forms a magnetic barrier reluctance rotor in the radial direction of the rotor, increases the tangential direction magnetic steels in the middle of the NS poles, increases the magnetic aggregation of the magnetic steels, improves the air gap magnetic field waveform while increasing the magnetic load of the motor, reduces the air gap magnetic field harmonic content, and improves the motor torque ripple, vibration and noise. Meanwhile, the scheme only needs to use one specification of magnetic steel, and the magnetic steel shape is regular, which greatly reduces the processing cost of the magnetic steel. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a schematic diagram of the cross-sectional structure of the application.

[0013] Figure 2 is a schematic diagram of the parameter label of the application.

[0014] Figure 3 is a torque ripple waveform diagram of the application.

[0015] Figure 4 is a cogging torque waveform diagram of the application.

[0016] Figure 5 is a back electromotive force waveform diagram of the application.

[0017] Figure 6 is a back electromotive force FFT decomposition diagram of the application.

[0018] Figure 7is a magnetic line distribution diagram of the motor of the present application.

[0019] Reference numerals: 1, rotor core; 21, slot one; 22, slot two; 3, slot three; 31, empty slot; 4, air slot; 5, magnetic steel; 6, magnetic bridge. DETAILED DESCRIPTION

[0020] The present application is further described in detail below with reference to the accompanying drawings.

[0021] Reference Figures 1-7 A rotor structure of a permanent magnet motor disclosed in the present application comprises a rotor core 1, wherein the rotor core 1 is provided with a plurality of placement slots, which are arranged in multiple layers in the direction towards the center of the circle, two layers in the present embodiment. The placement slots comprise slot one 21 and slot two 22, both ends of the slot one 21 are connected with the slot two 22, the slot two 22 is arranged obliquely, the slot two 22 at both ends of the slot one 21 is symmetrically arranged about the diameter passing through the midpoint of the slot one 21, and the circumferentially adjacent slot one 21 is further provided with a slot three 3, and the same specification magnetic steel 5 is arranged in the slot one 21 and the slot three 3. The placement slots and the slot three 3 are circumferentially and uniformly arranged on the rotor core 1. The slot three 3 is arranged along the q-axis direction. The slot two 22 in different layers and on the same side is parallel to each other, and the slot two 22 is parallel to the adjacent slot three 3.

[0022] The width of the magnetic steel 5 is W, the distance between the outer slot two 22 and the inner slot two 22 is A, 0.3W≤A≤0.8W, the distance between the inner slot two 22 and the slot three 3 is B, and the size relationship between B and W is 0.3W≤B≤W.

[0023] The adjacent slot three 3 is provided with an arc-shaped air slot 4, the air slot 4 takes the axis as the center, the outer edge radius of the air slot 4 is R2, and the distance between the bottom of the magnetic steel 5 in the slot three 3 and the center is R1, and 0.1L≤R2-R1≤0.2L. The tangential magnetic leakage of the magnetic steel 5 can be reduced, and the utilization rate of the magnetic steel 5 can be improved.

[0024] The end of the slot three 3 close to the axis is an empty slot 31, and the empty slot 31 and the air slot 4 form a magnetic bridge 6. By arranging the empty slot 31 and the air slot 4, the magnetic bridge 6 is formed at the core, so as to reduce the magnetic leakage. The outer end of the slot two 22 is also provided with a magnetic bridge 6. As shown in the figure, the magnetic bridge 6 effectively separates the magnetism, and improves the air gap magnetic density waveform and torque ripple. Figure 7

[0025] ​The distance between the magnetic steel 5 in the outer slot 21 and the outer circle of the rotor is H3, the radial distance between the magnetic steel 5 in the two-layer slot 21 is H2, and the distance between the magnetic steel 5 in the inner slot 21 and the air slot 4 is H1; the relationship between H1, H2 and H3 is 1≤H1:H2≤1.2 and 1≤H2:H3≤1.2; the size relationship between H3 and W is 0.5W≤H3≤W. By increasing the magnetic resistance of the d-axis and reducing the magnetic resistance of the q-axis magnetic circuit, the saliency ratio of the motor is improved.

[0026] The angle α (pole arc angle A) is formed between the rotation center O and the outer top point of the magnetic steel 5 in the outer slot 21, and the angle β (pole arc angle B) is formed between the rotation center O and the inner top point of the magnetic steel 5 in the inner slot 21, and 78°≤α*p≤90° and 120°≤β*p≤140°.

[0027] The implementation principle of the embodiment is that the rotor topology structure is arranged by the radial + tangential magnetic steel 5, which forms a magnetic barrier reluctance rotor in the radial direction of the rotor, and increases the tangential magnetic steel 5 in the middle of the NS pole, such as Figure 7 As shown in the motor magnetic line distribution diagram, by the above scheme, the magnetic steel 5 is aggregated, the magnetic load of the motor is improved, the air gap magnetic field waveform is improved, the air gap magnetic field harmonic content is reduced, the motor torque ripple, vibration and noise are improved. At the same time, the scheme only needs to use one specification of magnetic steel 5, and the shape of the magnetic steel 5 is regular, which greatly reduces the processing cost of the magnetic steel 5, and by setting the shape and arrangement mode of the magnetic steel 5, the pole arc coefficient is optimized, the air gap flux waveform is improved, and the influence on the back electromotive force waveform is improved, thereby reducing the vibration and noise of the motor.

[0028] The embodiments of the specific embodiment are the preferred embodiments of the application, and do not limit the protection scope of the application, so that: any equivalent changes made according to the structure, shape, principle of the application should be covered within the protection scope of the application.

Claims

1. A permanent magnet electric machine rotor structure, characterized by: The rotor core (1) is provided with a placing slot, the placing slot comprises a slot one (21) and a slot two (22), both ends of the slot one (21) are connected with the slot two (22), the slot two (22) is arranged obliquely, the slot two (22) at both ends of the slot one (21) is symmetrically arranged, a slot three (3) is further arranged between the circumferentially adjacent slot one (21), and the slot one (21) and the slot three (3) are both provided with a magnetic steel (5).

2. A permanent magnet machine rotor structure according to claim 1, characterized in that: The placing slot is arranged in multiple layers in the direction towards the center of the circle.

3. A permanent magnet machine rotor structure according to claim 1, characterized in that: The outer end of the slot three (3) and the slot two (22) is provided with a magnetic isolation bridge (6).

4. A permanent magnet machine rotor structure according to claim 2, characterized in that: The placing slot has two layers, the width of the magnetic steel (5) is W, the distance between the outer layer slot two (22) and the inner layer slot two (22) is A, 0.3W≤A≤0.8W, the distance between the inner layer slot two (22) and the slot three (3) is B, and the size relationship between B and W is 0.3W≤B≤W.

5. A permanent magnet machine rotor structure according to claim 1, characterized by: The adjacent slot three (3) is provided with an arc-shaped air slot (4), the air slot (4) takes the center of the shaft as the center of the circle, the outer edge radius of the air slot (4) is R2, the distance between the bottom of the magnetic steel (5) in the slot three (3) and the center of the circle is R1, and 0.1L≤R2-R1≤0.2L.

6. A permanent magnet machine rotor structure according to claim 5, characterised in that: The distance between the magnetic steel (5) in the outer layer slot one (21) and the rotor outer circle is H3, the radial distance between the magnetic steels (5) in the two layer slot one (21) is H2, the distance between the magnetic steel (5) in the inner layer slot one (21) and the air slot (4) is H1, the relationship among H1, H2 and H3 is 1≤H1:H2≤1.2 and 1≤H2:H3≤1.2, and the size relationship between H3 and W is 0.5W≤H3≤W.

7. A permanent magnet machine rotor structure as claimed in claim 2, characterised in that: The angle α is formed by the connection line between the outer top point of the magnetic steel (5) in the outer layer slot one (21) and the rotation center O, the angle β is formed by the connection line between the inner top point of the magnetic steel (5) in the inner layer slot one (21) and the rotation center O, 78°≤α*p≤90° and 120°≤β*p≤140°.

8. A permanent magnet machine rotor structure as claimed in claim 1, characterized by: The magnetic steels (5) in the slot one (21) and the slot three (3) are of the same specification.

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