Permanent magnet motor rotor structure

Abstract

The application relates to a permanent magnet motor rotor structure and relates to the technical field of permanent magnet motors, which comprises a rotor core, wherein the rotor core is provided with a placing groove, the placing groove comprises groove one and groove two, the two ends of the groove one are connected with the groove two, the groove two is arranged in an inclined mode, the groove two at the two ends of the groove one is arranged in a symmetrical mode, groove three is further arranged between the circumferentially adjacent groove one, and the same specification magnetic steel is arranged in the groove one and the groove three. The application has the advantages that the air gap magnetic field waveform can be improved, the air gap magnetic field harmonic content can be reduced, and the motor torque ripple, vibration and noise can be improved.

Description

Technical Field

[0001] This application relates to the technical field of permanent magnet motors, and in particular to a rotor structure for a permanent magnet motor. Background Technology

[0002] With the development of power electronics technology, permanent magnet synchronous motors have been widely used in the market. However, due to the high price of neodymium iron boron (NdFeB) materials, which are non-renewable resources, permanent magnet assisted reluctance synchronous motors using ferrite permanent magnets have been developing rapidly in recent years to replace rare earth permanent magnet motors. However, the existing permanent magnet assisted reluctance synchronous motors on the market basically adopt a multi-layer radial magnet arrangement structure. Especially for low-power permanent magnet assisted reluctance synchronous motors, the rotor core space is limited. In order to maximize the magnetic flux, the magnet shape is often designed as an arc. Although this solves the power density problem of permanent magnet assisted reluctance synchronous motors, the air gap magnetic field distribution of this rotor topology is still close to a square wave, and the cogging torque, torque pulsation, and noise of the motor cannot be effectively controlled. Summary of the Invention

[0003] To address the shortcomings of existing technologies, one of the objectives of this application is to provide a permanent magnet motor rotor structure that has the advantages of improving the air gap magnetic field waveform, reducing the harmonic content of the air gap magnetic field, and improving motor torque pulsation, vibration, and noise.

[0004] The above-mentioned objective of this application is achieved through the following technical solution:

[0005] A permanent magnet motor rotor structure includes a rotor core. The rotor core is provided with placement slots, including slot 1 and slot 2. Both ends of slot 1 are connected to slot 2. Slot 2 is inclined and slot 2 is symmetrically arranged at both ends of slot 1. Slot 3 is also provided between adjacent slot 1 in the circumferential direction. Magnets of the same specification are provided in slot 1 and slot 3.

[0006] In a preferred embodiment, this application can be further configured such that the placement slots are arranged in multiple layers in the direction toward the center.

[0007] In a preferred embodiment, this application can be further configured such that magnetic bridges are provided at the outer ends of both slot three and slot two.

[0008] In a preferred embodiment, this application can be further configured as follows: the placement slot has two layers, the width of the magnet is W, the distance between the outer slot and the inner slot is A, 0.3W≤A≤0.8W, the distance between the inner slot and the third slot is B, and the dimensional relationship between B and W is 0.3W≤B≤W.

[0009] In a preferred embodiment, this application can be further configured such that: an arc-shaped air groove is provided between adjacent slots three, the air groove is centered on the axis, the outer radius of the air groove is R2, and the bottom of the magnet in slot three is R1 from the center of the circle, and 0.1L≤R2-R1≤0.2L.

[0010] In a preferred embodiment, this application can be further configured as follows: the distance between the magnet in the outer slot 1 and the outer circle of the rotor is H3, the radial distance between the magnets in the two slot 1s is H2, and the distance between the magnet in the inner slot 1 and the air slot is H1; the relationship between H1, H2, and H3 is 1≤H1:H2≤1.2, 1≤H2:H3≤1.2; the dimensional relationship between H3 and W is 0.5W≤H3≤W.

[0011] In a preferred embodiment, this application can be further configured such that: with the rotation center as point O, the line connecting the outer vertex of the magnet in the outer slot 1 forms an angle α, and the line connecting the inner vertex of the magnet in the inner slot 1 forms an angle β, where 78°≤α*p≤90°, and 120°≤β*p≤140°.

[0012] In a preferred embodiment, this application can be further configured such that the magnets in slot one and slot three have the same specifications.

[0013] This application has the following advantages:

[0014] By arranging the rotor topology using radial magnets in slot one and tangential magnets in slot three, a magnetic barrier reluctance rotor is formed in the radial direction. Furthermore, tangential magnets are added between the N and S poles to enhance the magnetizing effect, increasing the motor's magnetic load while improving the air gap magnetic field waveform, reducing harmonic content, and mitigating torque pulsation, vibration, and noise. This solution also requires only one type of magnet with a regular shape, significantly reducing magnet manufacturing costs. Attached Figure Description

[0015] Figure 1 This is a cross-sectional structural diagram of this application.

[0016] Figure 2 This is a schematic diagram of the parameter labels in this application.

[0017] Figure 3 This is the torque pulsation waveform diagram of this application.

[0018] Figure 4 This is the cogging torque waveform diagram of this application.

[0019] Figure 5 This is the back electromotive force waveform diagram of this application.

[0020] Figure 6 This is the back EMF FFT decomposition diagram of this application.

[0021] Figure 7 This is a diagram showing the distribution of magnetic field lines of the motor in this application.

[0022] Attached reference numerals: 1. Rotor core; 21. Slot 1; 22. Slot 2; 3. Slot 3; 31. Empty slot; 4. Air slot; 5. Magnet; 6. Magnetic bridge. Detailed Implementation

[0023] The present application will be further described in detail below with reference to the accompanying drawings.

[0024] Reference Figures 1-7 This application discloses a permanent magnet motor rotor structure, including a rotor core 1. The rotor core 1 has placement slots arranged in multiple layers facing the center; in this embodiment, there are two layers. The placement slots include slot 1 21 and slot 22. Both ends of slot 1 21 are connected to slot 22. Slot 22 is inclined, and the slots 22 at both ends of slot 1 21 are symmetrically arranged about the diameter passing through the midpoint of slot 1 21. A slot 3 is also provided between adjacent slots 1 21 in the circumferential direction. Both slot 1 21 and slot 3 contain magnets 5 of the same specification. The placement slots and slot 3 are evenly distributed circumferentially on the rotor core 1. Slot 3 is arranged along the q-axis direction. Slots 22 on the same side but in different layers are parallel to each other, and slot 22 and adjacent slot 3 are parallel.

[0025] Let the width of magnet 5 be W, the distance between the outer groove 22 and the inner groove 22 be A, 0.3W≤A≤0.8W, the distance between the inner groove 22 and the third groove 3 be B, and the dimensional relationship between B and W is 0.3W≤B≤W.

[0026] An arc-shaped air groove 4 is provided between adjacent grooves 3. The air groove 4 is centered on the axis and has an outer radius of R2. At the same time, the bottom of the magnet 5 in groove 3 is R1 away from the center of the circle, and 0.1L≤R2-R1≤0.2L. This can reduce the leakage flux of the tangential magnet 5 and improve the utilization rate of the magnet 5.

[0027] The end of slot 3 near the axis is an empty slot 31, which, together with air slot 4, forms a magnetic isolation bridge 6. By setting the empty slot 31 and air slot 4, a magnetic isolation bridge 6 is formed at the iron core, thereby reducing magnetic leakage. A magnetic isolation bridge 6 is also provided at the outer end of slot 22. For example... Figure 7 As shown, the magnetic isolation bridge 6 effectively isolates the magnetic field and improves the air gap magnetic flux density waveform and torque pulsation.

[0028] The distance between the magnet 5 in the outer slot 21 and the outer circle of the rotor is H3; the radial distance between the magnets 5 in the two slots 21 is H2; and the distance between the magnet 5 in the inner slot 21 and the air slot 4 is H1. The relationships between H1, H2, and H3 are 1≤H1:H2≤1.2 and 1≤H2:H3≤1.2. The dimensional relationship between H3 and W is 0.5W≤H3≤W. By increasing the magnetic reluctance of the d-axis and simultaneously reducing the magnetic reluctance of the q-axis magnetic circuit, the saliency ratio of the motor is increased.

[0029] With the rotation center as point O, the line connecting the magnet 5 in the outer slot 21 forms an angle α (polar arc angle A), and the line connecting the magnet 5 in the inner slot 21 forms an angle β (polar arc angle B). 78°≤α*p≤90°, 120°≤β*p≤140°.

[0030] The implementation principle of this embodiment is as follows: by arranging the rotor topology with radial and tangential magnets 5, a magnetic barrier type reluctance rotor is formed in the radial direction of the rotor, and a tangential magnet 5 is added between the N and S poles, as shown below. Figure 7 As shown in the motor magnetic field distribution diagram, the above scheme not only increases the magnetic focusing effect of magnet 5, improving the motor's magnetic load, but also improves the air gap magnetic field waveform, reduces the harmonic content of the air gap magnetic field, and improves the motor's torque pulsation, vibration, and noise. Furthermore, this scheme only requires the use of one specification of magnet 5, and the magnet 5 has a regular shape, significantly reducing the processing cost of magnet 5. At the same time, by setting the shape and arrangement of magnet 5, the pole arc coefficient is optimized, improving the air gap magnetic flux density waveform, thereby improving the waveform affecting the back electromotive force, and thus reducing the motor's vibration and noise.

[0031] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A permanent magnet electric machine rotor structure, characterized by: The application relates to a rotor core (1) provided with a placing slot, the placing slot comprising a slot one (21) and a slot two (22), both ends of the slot one (21) being connected with the slot two (22), the slot two (22) being arranged in an inclined mode, the slot two (22) at both ends of the slot one (21) being arranged in a symmetrical mode, a slot three (3) being further arranged between circumferentially adjacent slot ones (21), and the slot one (21) and the slot three (3) being provided with a magnetic steel (5); the placing slot is arranged in multiple layers in a direction towards a circle center; the slot three (3) and the outer end of the slot two (22) are provided with a magnetic isolation bridge (6); 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; the adjacent slot threes (3) are provided with an arc-shaped air slot (4), the air slot (4) takes the axis center as a circle center, 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 circle center is R1, and 0.1L<=R2-R1<=0.2L, L is the length of the magnetic steel; the rotation center is taken as an O point, the magnetic steel (5) in the outer layer slot one (21) forms an angle alpha with the outer top point, the magnetic steel (5) in the inner layer slot one (21) forms an angle beta with the inner top point, 78<=alpha*p<=90, 120<=beta*p<=140; the magnetic steel (5) in the slot one (21) and the slot three (3) has the same specification.

2. A permanent magnet machine rotor structure according to claim 1, characterized 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 of the magnetic steel (5) in the two layer slot ones (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, 1<=H2:H3<=1.2; the size relationship between H3 and W is 0.5W<=H3<=W.

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