CN110635594A

CN110635594A - Novel permanent magnet synchronous motor rotor structure for electric automobile

Info

Publication number: CN110635594A
Application number: CN201910789608.XA
Authority: CN
Inventors: 刘栋良; 屈峰; 崔丽丽; 李阿强; 杨响攀
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2019-08-26
Filing date: 2019-08-26
Publication date: 2019-12-31

Abstract

The invention discloses a novel permanent magnet synchronous motor rotor structure for an electric automobile, wherein a regular polygon is established by using the circle center of a permanent magnet synchronous motor rotor punching sheet on a permanent magnet synchronous motor with 4 pairs of poles and 48 grooves and uniform air gap intervals, R1 is more than R2, wherein R1 is the radius of the permanent magnet synchronous motor rotor punching sheet, R2 is the radius of the regular polygon, the center point of the circle center of the permanent magnet synchronous motor rotor is taken as the origin, the center point of the vertical line from the origin to the octagonal edge is taken as a dot, and the arc with the line segment from the dot to the nearest octagonal vertex as the radius is taken as the outer contour of the new permanent magnet synchronous motor rotor punching sheet; then, taking the original point as the center of a circle and taking R3 as the radius to make a circle, and overlapping the circle with the outer contour of the rotor sheet of the new permanent magnet synchronous motor to obtain a rotor structure; the invention uses non-uniform air gaps, so that the air gap flux density has sinusoidal distribution, the harmonic content is reduced, the radial force wave is well improved, and the vibration and noise of the permanent magnet synchronous motor are reduced.

Description

Novel permanent magnet synchronous motor rotor structure for electric automobile

Technical Field

The invention belongs to the field of permanent magnet synchronous motors for electric vehicles; in particular to a novel permanent magnet synchronous motor rotor structure for optimizing the radial force waveform of a permanent magnet synchronous motor.

Background

In recent years, with the gradual implementation of policies in the electric automobile industry and the growing concern of people about environmental energy problems, electric automobiles are gradually selected by more and more consumers. The permanent magnet synchronous motor has the advantages of high efficiency, high rotating speed, high power density and the like, becomes the first choice of the permanent magnet synchronous motor for vehicles, and most of the permanent magnet synchronous motors are used as power sources in domestic markets at present.

Although the permanent magnet synchronous motor has remarkable advantages, the noise caused by the permanent magnet synchronous motor becomes a new concern because the electric automobile does not have the engine noise of rolling, and a product with good NVH performance is expected by all large factories and consumers.

At present, common permanent magnet synchronous motors for vehicles are all built-in permanent magnet synchronous motors, and according to Maxwell's law:

in the formula: b is_r、B_tRespectively representing the radial flux density and the tangential flux density of the air-gap field, F_r、F_tRespectively representing radial and tangential electromagnetic forces, mu₀The permeability in vacuum is indicated. Because the tangential electromagnetic force acts on the stator core tooth part to cause the tooth part to deform tangentially, when the rigidity and the thickness of the stator tooth part are ensured, the vibration noise generated by the tangential electromagnetic force is very small and can be generally ignored. The radial electromagnetic force is a main cause of vibration noise of the motor. Conventional permanent magnet synchronous machines typically use rectangular permanent magnets, and circular rotor laminations. Under the condition of uniform air gaps, the air gap flux density of the rectangular permanent magnet synchronous motor is distributed in a trapezoidal mode, the flux density distribution has large harmonic content, serious radial force harmonic waves can be generated, motor vibration and noise are further caused, and the NVH (noise, vibration and harshness) characteristic of the whole vehicle is affected. The optimization of the radial electromagnetic force is mainly aimed at permanent magnet materials, magnetizing and stator and rotor slotting methods.

The technical characteristics are as follows: the novel rotor structure of the permanent magnet synchronous motor enables air gap distribution in the motor to have non-uniformly distributed air gap distribution. The non-uniform air gap distribution can enable the air gap flux density to present approximate sine distribution, so that the harmonic content of radial force waves is reduced, and the vibration and noise of the permanent magnet synchronous motor are further effectively reduced.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a novel permanent magnet synchronous motor rotor structure for an electric automobile.

The invention relates to a novel permanent magnet synchronous motor rotor structure for an electric automobile, which is characterized in that on a permanent magnet synchronous motor with 4 pairs of poles and 48 grooves and uniform air gap intervals, a regular polygon is established by taking the circle center of a rotor punching sheet of the permanent magnet synchronous motor, R1 is more than R2, wherein R1 is the radius of the rotor punching sheet of the permanent magnet synchronous motor, R2 is the radius of the regular polygon, the circle center point of the rotor of the permanent magnet synchronous motor is taken as an original point, the center point of a perpendicular line from the original point to an octagonal edge is taken as a round point, and an arc taking a line segment from the round point to the nearest octagonal peak as the radius is taken as the outer contour of the rotor punching; then, taking the original point as the circle center and taking R3 as the radius to make a circle, and overlapping the circle with the outer contour of the rotor punching sheet of the new permanent magnet synchronous motor to obtain the rotor structure of the novel permanent magnet synchronous motor for the electric automobile; wherein R1 > R3 > R2.

Preferably, the original permanent magnet synchronous motor stator and winding mode is used, Maxwell electromagnetic simulation is carried out, R2 and R3 are used as parameters, the motor air gap flux density total harmonic distortion rate is used as a reference target, parameter setting is carried out, and the optimal R2 and R3 are obtained. According to the structure of the original permanent magnet synchronous motor, the inner diameter of a stator core is 57mm, R2 is 53.2mm optimally, R3 is 56mm optimally, the maximum value of the air gap width is 1.1mm, and the minimum value is 0.7mm under the novel permanent magnet synchronous motor rotor structure.

Compared with the prior art, the invention has the following effects: the uniform air gap used by the existing permanent magnet synchronous motor has trapezoidal distribution of air gap flux density and larger harmonic content, which causes the radial force wave harmonic content of the permanent magnet synchronous motor to be larger and generates larger vibration noise. The novel rotor punching structure of the permanent magnet synchronous motor uses non-uniform air gaps, so that the air gap flux density is distributed sinusoidally, the harmonic content is reduced, the radial force wave is well improved, and the vibration and noise of the permanent magnet synchronous motor are reduced.

Drawings

FIG. 1: 4 pairs of permanent magnet synchronous motor rotor sheets with uniform air gaps are schematically shown in the structure;

FIG. 2: establishing an outline schematic diagram of the rotor punching sheet of the permanent magnet synchronous motor with an arc boundary according to the regular octagon;

FIG. 3: the outline schematic diagram of the rotor punching sheet of the novel permanent magnet synchronous motor;

FIG. 4: the structure schematic diagram of the novel permanent magnet synchronous motor rotor punching sheet;

FIG. 5: the novel permanent magnet synchronous motor rotor and stator air gap schematic diagram;

FIG. 6: 4 pairs of poles, 48 slots of uniform air gap permanent magnet synchronous motor air gap flux density schematic diagram;

FIG. 7: the radial force wave space distribution schematic diagram of the permanent magnet synchronous motor with the uniform air gaps of 4 pairs of poles and 48 slots;

FIG. 8: 4 pairs of poles, 48 slots of novel rotor, permanent magnet synchronous motor air gap flux density schematic diagram;

FIG. 9: the space distribution schematic diagram of the radial force wave of the permanent magnet synchronous motor under the novel rotor with 4 pairs of poles and 48 grooves;

FIG. 10: the air gap flux density Fourier decomposition schematic diagram of the permanent magnet synchronous motor with the uniform air gap and 48 pairs of poles;

FIG. 11: the Fourier decomposition schematic diagram of the air gap flux density of the permanent magnet synchronous motor under the novel rotor with 4 pairs of poles and 48 grooves;

FIG. 12: the Fourier decomposition schematic diagram of the radial force wave spatial distribution of the permanent magnet synchronous motor with the uniform air gaps of the 4 pairs of poles and 48 grooves;

FIG. 13: the Fourier decomposition schematic diagram of the radial force wave spatial distribution of the permanent magnet synchronous motor under the novel rotor with 4 pairs of poles and 48 grooves.

Detailed Description

The invention is innovated according to a rotor punching sheet (as shown in figure 1) of a 4-antipode 48-slot permanent magnet synchronous motor, a regular octagon with the radius of R2 is established by taking an original point O of the rotor punching sheet of the original permanent magnet synchronous motor as the center, R2 is smaller than R1 (the outer diameter of the original permanent magnet synchronous motor punching sheet), then an arc intersection is made with the middle point O1 of a perpendicular line OB of one side AC of the regular octagon by taking the point O to the middle point O1 of the perpendicular line OB of the regular octagon as the center and taking the vertex A of the regular octagon from O1 as the radius R to obtain an arc AC, and other eight. A circle with the center at O point and the radius at R3 intersects the above-mentioned circular arc as shown in FIG. 3, wherein R2< R3< R1. The outermost arc line is taken as the novel rotor outer contour, and the original electromagnetic scheme parameters are set as shown in figure 4. The stator structure and the winding mode of the original permanent magnet synchronous motor are used, R2 and R3 are used as parameters, and Maxwell is used for carrying out parametric analysis by taking the air gap flux density distortion rate as a reference target, wherein R2 and R3 are controlled to control an air gap minimum value and an air gap maximum value respectively, as shown in FIG. 5. According to the structure of the original permanent magnet synchronous motor, the inner diameter of a stator core is 57mm, R2 is 53.2mm optimally, R3 is 56mm optimally, the maximum value of the air gap width is 1.1mm, and the minimum value is 0.7mm under the novel permanent magnet synchronous motor rotor structure. Compared with the original structure, the novel permanent magnet synchronous motor has better sine property through analysis and comparison of air gap flux density and radial force, as shown in figures 6-9, and the harmonic content amplitude of the novel permanent magnet synchronous motor structure can be greatly improved through Fourier decomposition. Fourier decomposition of the spatial distribution of air gap magnetic density and radial force wave under the two structures is shown in fig. 10, 11, 12 and 13. The result analysis shows that the novel rotor structure is greatly optimized.

Claims

1. The utility model provides a novel PMSM rotor structure for electric automobile car which characterized in that: on a permanent magnet synchronous motor with 4 pairs of poles and 48 slots and uniform air gap intervals, establishing a regular polygon by using the circle center of a rotor punching sheet of the permanent magnet synchronous motor, and enabling R1 to be larger than R2, wherein R1 is the radius of the rotor punching sheet of the permanent magnet synchronous motor, R2 is the radius of the regular polygon, the circle center point of the rotor of the permanent magnet synchronous motor is taken as an origin, the center point of a perpendicular line from the origin to an octagonal side is taken as a dot, and an arc with the line segment from the dot to the vertex of the octagonal closest distance as the radius is taken as the outer contour of the rotor punching sheet of the new permanent magnet; then, taking the original point as the circle center and taking R3 as the radius to make a circle, and overlapping the circle with the outer contour of the rotor punching sheet of the new permanent magnet synchronous motor to obtain the rotor structure of the novel permanent magnet synchronous motor for the electric automobile; wherein R1 > R3 > R2.

2. The novel permanent magnet synchronous motor rotor structure for the electric automobile according to claim 1, characterized in that: the method is characterized in that an original permanent magnet synchronous motor stator and winding mode is used, through Maxwell electromagnetic simulation, R2 and R3 are used as parameters, the motor air gap magnetic density total harmonic distortion rate is used as a reference target, parameter setting is carried out, and the optimal R2 and R3 are obtained.

3. The utility model provides a novel PMSM rotor structure for electric automobile car which characterized in that: according to the structure of the original permanent magnet synchronous motor, the inner diameter of a stator core is 57mm, R2 is 53.2mm optimally, R3 is 56mm optimally, the maximum value of the air gap width is 1.1mm, and the minimum value is 0.7mm under the novel permanent magnet synchronous motor rotor structure.