CN210629214U

CN210629214U - Rotor structure and permanent magnet synchronous motor

Info

Publication number: CN210629214U
Application number: CN201920917036.4U
Authority: CN
Inventors: 陈益辉; 黄佳; 王殿嵩; 龚文胜
Original assignee: United Automotive Electronic Systems Co Ltd
Current assignee: United Automotive Electronic Systems Co Ltd
Priority date: 2019-06-18
Filing date: 2019-06-18
Publication date: 2020-05-26
Anticipated expiration: 2029-06-18

Abstract

The utility model provides a rotor structure and a permanent magnet synchronous motor, which comprises a rotor body and a plurality of pairs of magnetic poles; the magnetic poles are arranged on the rotor body; a plurality of pairs of first grooves are formed in the outer diameter of the rotor body; an angle formed by a connecting line of the center point of the first groove and the center of the rotor body and the straight axis is theta, wherein theta is in an electrical angle ranging from 46-47 degrees. Through being equipped with first recess on rotor body's external diameter, can make the part originally pass through the magnetic flux that quadrature axis magnetic bridge got into the rotor from the air gap and change the route, and make the magnetic circuit saturation degree on quadrature axis magnetic bridge both sides increase, the magnetic conductance reduces, has more effectively reduced torque ripple and no-load back emf harmonic, and the suppression effect is better.

Description

Rotor structure and permanent magnet synchronous motor

Technical Field

The utility model relates to the technical field of electric machines, in particular to rotor structure and PMSM.

Background

The permanent magnet synchronous motor is a motor which utilizes a permanent magnet to provide a magnetic field, and gradually becomes the first choice of a driving motor in a hybrid electric vehicle and a pure electric vehicle with the advantages of high power, high torque density, high efficiency and the like.

In the existing permanent magnet synchronous motor, a permanent magnet (such as magnetic steel) on a rotor generally adopts a surface-mounted structure or a built-in structure. The magnetic steel in the built-in permanent magnet synchronous motor is usually arranged in a magnetic steel groove on a rotor punching sheet. Because the built-in permanent magnet synchronous motor can generate reluctance torque through the salient pole effect of the rotor, the torque level is improved, the field weakening speed regulation range is expanded, and the copper consumption in low-speed and large-torque conditions is reduced, the built-in permanent magnet synchronous motor is widely applied.

However, the salient pole effect of the rotor also causes cogging torque, and the inductance difference between the direct axis and the quadrature axis (namely d axis and q axis) of the permanent magnet synchronous motor is increased, so that the harmonic content of a load magnetic field is increased, and even torque fluctuation during load is caused. These factors can cause vibration and noise, increase passenger discomfort, and may also cause the inconvenience of matching the motor and controller.

To solve the above technical problems, the prior art generally adopts the following two methods:

the first method is to select reasonable pole and groove matching;

the second method is to adopt a stator chute or a rotor segmented oblique pole to reduce torque fluctuation; as shown in fig. 1, the magnetic poles 2 of the rotor 1 are axially divided into several segments and are circumferentially offset by a certain angle.

The inventor finds that both methods have certain problems, specifically as follows:

1) permanent magnet synchronous motors using distributed windings generally have longer winding tips, which are not suitable for certain entire vehicle structures with limited axial space;

2) the adoption of the stator chute can increase the wire embedding difficulty and increase the using amount of the enameled copper wire; the adoption of the rotor segmented oblique poles not only needs to add an additional tool clamp, but also can generate additional magnetic leakage between adjacent lamination groups, so that the performance of the motor is weakened, and the rotor segmented oblique poles are only suitable for permanent magnet synchronous motors with more segments or longer axial effective lengths; therefore, the peak characteristics of the driving motor are reduced due to the stator skewed slots and the rotor segmented skewed poles, and if the performance of the driving motor is ensured, the axial length needs to be increased, which brings extra material cost and installation space cost; more than this, stator skewed slot and rotor segmentation skewed pole all can produce periodic axial component on the rotor, increase the probability of failure of bearing, still can bring certain noise and vibration simultaneously.

SUMMERY OF THE UTILITY MODEL

The utility model provides a rotor structure and PMSM to realize effectively reducing the invention purpose of counter potential harmonic and torque ripple when no-load.

The utility model provides a rotor structure, which comprises a rotor body and a plurality of pairs of magnetic poles; the magnetic poles are arranged on the rotor body; a plurality of pairs of first grooves are formed in the outer diameter of the rotor body; an angle formed by a connecting line of the center point of the first groove and the center of the rotor body and the straight axis is theta, wherein theta is in an electrical angle ranging from 46-47 degrees.

Optionally, in the rotor structure, the first groove is in smooth transition connection with the outer periphery of the rotor body.

Optionally, in the rotor structure, a cross section of the first groove along the radial direction of the rotor body is a sector, a V shape, or a frame shape.

Optionally, in the rotor structure, a plurality of pairs of magnetic steel grooves are formed in the rotor body; the number of pairs of the magnetic steel grooves 11 is the same as that of the magnetic poles, and a pair of the magnetic poles are arranged in a pair of the magnetic steel grooves.

Optionally, in the rotor structure, each pair of the first grooves is located on both sides of the intersecting axis.

Optionally, in the rotor structure, a second groove is formed in one end, close to the intersecting axis, of the magnetic steel groove.

Optionally, in the rotor structure, a cross section of the second groove along the radial direction of the rotor body is a sector, a V shape, or a frame shape.

Secondly, the utility model also provides a PMSM, include as above arbitrary one the rotor structure.

Optionally, in the permanent magnet synchronous motor, the permanent magnet synchronous motor further includes a stator; the rotor structure is arranged in the stator; wherein a certain air gap is provided between the stator and rotor structures.

Optionally, in the permanent magnet synchronous motor, each pair of magnetic steel slots is symmetrically arranged on two sides of the same quadrature axis.

Compared with the prior art, the rotor structure provided by the utility model has the advantages that the first groove is arranged on the outer diameter of the rotor body, and the first groove enables part of the original magnetic flux entering the rotor from the air gap through the quadrature axis magnetic bridge to change the path, the saturation degree of the magnetic circuit at two sides of the quadrature axis magnetic bridge is increased, and the magnetic conductance is reduced; therefore, on one hand, the content of air gap flux density harmonic waves is reduced, on the other hand, the content of the air gap flux density is reduced, and simultaneously, the content of fundamental waves is increased, so that the sine degree of the air gap flux density is improved, the cogging effect caused by stator slotting is weakened, and the cogging torque is reduced; meanwhile, the magnetic resistance of a quadrature-axis magnetic circuit is increased, and the inductance of a quadrature axis is reduced, so that the salient pole effect of the rotor is weakened, and the torque fluctuation during loading is reduced; moreover, the lowest point positions of the first grooves are related to the corresponding magnetic pole lower straight axes, and torque fluctuation and no-load back electromotive force harmonics are more effectively reduced at an electrical angle of 46-47 degrees from two sides of the corresponding magnetic pole straight axes, so that the suppression effect is better.

Drawings

FIG. 1 is a schematic view of a prior art rotor segmented skewed pole;

fig. 2 is a schematic cross-sectional view of a quarter-rotor according to an embodiment of the present invention;

fig. 3 is another schematic cross-sectional view of a quarter-rotor according to an embodiment of the present invention;

fig. 4 is yet another schematic cross-sectional view of a quarter-rotor of an embodiment of the invention;

FIG. 5 is a no-load back emf harmonic plot for a prior art permanent magnet synchronous motor;

fig. 6 is a no-load back electromotive force harmonic diagram of the permanent magnet synchronous motor according to the embodiment of the present invention;

fig. 7 is a tooth space torque comparison diagram of the existing permanent magnet synchronous motor and the permanent magnet synchronous motor of the embodiment of the present invention.

Wherein the reference numbers of the embodiment of the utility model are explained as follows:

11-magnetic steel grooves; 12-a rotor body; 13-a first groove; 14-a second groove; 15-stator.

Detailed Description

In order to make the objects, advantages and features of the present invention clearer, the rotor structure and the permanent magnet synchronous motor provided by the present invention are further described in detail with reference to fig. 2-7. It should be noted that the drawings are in simplified form and are not to precise scale, and are provided for convenience and clarity in order to facilitate the description of the embodiments of the present invention.

Fig. 2 is a schematic view of a sectional shape of a first groove of a quarter-rotor of the present embodiment along a radial direction of the rotor body is a sector; fig. 3 is a schematic view of a cross-sectional shape of a first groove of a quarter-rotor of an embodiment of the present invention along a radial direction of the rotor body is a V shape; fig. 4 is a schematic view of the first groove of the quarter-rotor according to the embodiment of the present invention, which has a frame-shaped cross-section along the radial direction of the rotor body.

Referring to fig. 2-4, a rotor structure is provided, which includes a rotor body 12 and a plurality of pairs of magnetic poles; the magnetic poles are arranged on the rotor; the magnetic pole is used for providing a magnetic circuit; a plurality of pairs of first grooves 13 are formed in the outer diameter of the rotor body 12; an angle formed by a line connecting the center point of the first groove 13 and the center of the rotor body 12 and the straight axis d is θ, wherein θ is in a range of 46-47 ° in electrical angle.

Wherein, the rotor body 12 is provided with a plurality of pairs of magnetic steel grooves 11; the number of pairs of the magnetic steel slots 11 is the same as that of the magnetic poles, and a pair of the magnetic poles are placed in a pair of the magnetic steel slots 11 to provide a magnetic circuit.

By arranging the first grooves 13 on the outer diameter of the rotor body 12, and symmetrically arranging each pair of the first grooves 13 on two sides of the quadrature axis, part of the original magnetic flux entering the rotor from the air gap through the quadrature axis q magnetic bridge is changed into the magnetic flux entering the rotor from the first grooves 12 through the quadrature axis q magnetic bridge through the first grooves 13, the saturation degree of the magnetic paths on two sides of the quadrature axis q magnetic bridge is increased, and the magnetic conductance is reduced; therefore, on one hand, the content of air gap flux density harmonic waves is reduced, on the other hand, the content of the air gap flux density is reduced, and simultaneously, the content of fundamental waves is increased, so that the sine degree of the air gap flux density is improved, the cogging effect caused by slotting the stator 15 is weakened, and the cogging torque is reduced; meanwhile, the magnetic resistance of a quadrature-axis q magnetic circuit is increased, and the inductance of the quadrature-axis q is reduced, so that the salient pole effect of the rotor is weakened, and the torque fluctuation during loading is reduced; moreover, the lowest point positions of the first grooves 13 are related to the corresponding direct axes d, and torque fluctuation and no-load back electromotive force harmonics are more effectively reduced at 46-47 ° electrical angles from both sides of the direct axes d of the corresponding magnetic poles, and the suppression effect is better.

Here, regarding the direct axis d and the quadrature axis q, those skilled in the art are familiar with: in the permanent magnet synchronous motor control, in order to obtain the control characteristic similar to a direct current motor, a coordinate system is established on a rotor, the coordinate system and the rotor rotate synchronously, the direction of a rotor magnetic field is taken as a d axis (namely a straight axis d), and the direction vertical to the rotor magnetic field is taken as a q axis (namely an intersecting axis), so that a mathematical model of the motor is converted into the coordinate system, the decoupling of the d axis and the q axis can be realized, and the good control characteristic can be obtained.

Preferably, the first groove 13 is smoothly transitionally connected with the outer periphery of the rotor body 12, for example, by rounding off, so that stress concentration can be prevented and structural strength can be ensured. Wherein, the section of the first groove 13 along the radial direction of the rotor body 12 is fan-shaped, V-shaped or frame-shaped. However, the present invention is not limited to the cross-sectional shape of the first groove 13 along the radial direction of the rotor body 12, and the structural shape of the first groove 13 along the radial direction of the rotor body 12 is protected by the present invention as long as the structural shape is easy to process, can prevent stress concentration, and can ensure structural strength.

One end of the magnetic steel slot 11 close to the quadrature axis is provided with a second groove 14, the second groove 14 can increase the magnetic resistance of a quadrature axis q magnetic circuit, and the inductance of the quadrature axis q becomes small, so that the salient pole effect of the rotor is weakened, and the torque fluctuation during loading is reduced.

Meanwhile, as the inductance difference between the direct axis d and the quadrature axis q becomes smaller, the content of the harmonic wave of the load magnetic field is also reduced, so that the counter potential harmonic wave is reduced. Moreover, the second groove 14 also breaks the leakage flux path near the corner of the magnetic pole, so that the leakage flux is reduced, the main flux is increased, the problem of reduction of reluctance torque caused by reduction of inductance difference between the direct axis d and the quadrature axis q is compensated, and the reluctance torque is balanced. And then, the second groove 14 is arranged on the magnetic steel groove 11, so that the second groove and the magnetic steel groove 11 can be integrally formed, and thus, the processing steps can be reduced, and the production cost can be saved.

Wherein, the section of the second groove 14 along the radial direction of the rotor body 12 is fan-shaped, V-shaped or frame-shaped. However, the present invention is not limited to the shape of the radial cross section of the second groove 14 along the rotor body 12, and the present invention is intended to protect the structural shape of the radial cross section of the second groove 14 along the rotor body 12, which is capable of reducing the salient pole effect of the rotor by increasing the magnetic resistance of the magnetic path of the quadrature axis q and reducing the inductance of the quadrature axis q, thereby reducing the effect of torque ripple during loading.

In particular, the present embodiment also provides a permanent magnet synchronous motor including the rotor structure of the above embodiment. The permanent magnet synchronous motor adopting the rotor structure of the embodiment has low noise and good vibration resistance.

Referring to fig. 2-4, the permanent magnet synchronous motor further includes a stator 15, and the rotor is disposed in the stator 15, wherein a certain air gap (i.e., a gap) is formed between the stator 15 and the rotor, and the center of the first groove 13 on the rotor body 12 is located in the air gap, i.e., the center of the first groove 13 is located between the outer circle of the rotor body 12 and the inner circle of the stator 15.

Typically, the rotor body 12 is provided with a plurality of magnetic steel slots 11, and each magnetic steel slot 11 is used for accommodating one magnetic pole. The plurality of magnetic steel grooves 11 are distributed to form a plurality of pairs, and each pair of magnetic steel grooves 11 is symmetrical about the quadrature axis q so as to ensure the symmetry of the magnetic circuit. Among these, the person skilled in the art knows: the number of the magnetic steel grooves 11 arranged on the rotor body 12 is consistent with the number of the coils used on the permanent magnet synchronous motor.

Next, referring to fig. 5-6, fig. 5 is a no-load back electromotive force harmonic diagram of a conventional permanent magnet synchronous motor, and fig. 6 is a no-load back electromotive force harmonic diagram of the permanent magnet synchronous motor of the present embodiment.

As shown in fig. 5-6, by means of said first groove 13, the shoulder a (enclosed by several solid circles in the figure) of the no-load back-emf harmonic shown in fig. 5 can be flattened to the no-load back-emf harmonic shown in fig. 6, reducing the content of the harmonics 5 and 7 in the air gap flux density harmonic between the rotor and the stator 15. Specifically, following table provides current PMSM again and the utility model discloses a PMSM during operation's no-load back electromotive force harmonic content's the distribution condition:

as shown in the table above, after the second groove 14 is formed in the magnetic steel groove 11 and the first groove 13 is formed in the outer periphery of the rotor body 12, the content of the idle-load back electromotive force harmonic is significantly reduced in 3 th, 5 th, 7 th and 11 th harmonics.

Referring to fig. 7, fig. 7 is a graph of cogging torque varying with the position of the rotor, the abscissa is the rotational position of the rotor, which uses the angle as the unit, the ordinate is the torque, and uses Nm as the unit, wherein curve 1 is the cogging torque value of the existing permanent magnet synchronous motor, and curve 2 is the cogging torque value of the permanent magnet synchronous motor of the present invention. As shown in fig. 7, the cogging torque of the present invention can be reduced to about 50% of the conventional cogging torque.

The above description is only for the preferred embodiment of the present invention and is not intended to limit the scope of the present invention, and any modification and modification made by those skilled in the art according to the above disclosure are all within the scope of the claims.

Claims

1. A rotor structure is characterized by comprising a rotor body and a plurality of pairs of magnetic poles; the magnetic poles are arranged on the rotor body; a plurality of pairs of first grooves are formed in the outer diameter of the rotor body; an angle formed by a connecting line of the center point of the first groove and the center of the rotor body and the straight axis is theta, wherein theta is in an electrical angle ranging from 46-47 degrees.

2. The rotor structure of claim 1, wherein the first groove is in smooth transition with the outer circumference of the rotor body.

3. The rotor structure according to claim 1, wherein the first groove has a sector shape, a V shape, or a frame shape in a cross section in a radial direction of the rotor body.

4. The rotor structure of claim 1, wherein the rotor body is provided with a plurality of pairs of magnetic steel slots; the number of pairs of the magnetic steel grooves is the same as that of the magnetic poles, and a pair of the magnetic poles are placed in a pair of the magnetic steel grooves.

5. A rotor structure according to claim 4, wherein each pair of said first recesses is located on either side of the axis of intersection.

6. The rotor structure of claim 5, wherein the magnetic steel slot is provided with a second groove at an end near the quadrature axis.

7. The rotor structure according to claim 6, wherein the second groove has a sector shape, a V shape, or a frame shape in a cross section in a radial direction of the rotor body.

8. A permanent magnet synchronous machine, characterized in that it comprises a rotor structure according to any of claims 1 to 7.

9. The permanent magnet synchronous machine of claim 8, further comprising a stator; the rotor structure is arranged in the stator; wherein an air gap is provided between the stator and rotor structures.

10. The permanent magnet synchronous motor of claim 8, wherein each pair of magnetic steel slots are symmetrically arranged on two sides of the same quadrature axis.