CN114270663B

CN114270663B - Rotor

Info

Publication number: CN114270663B
Application number: CN202080059249.3A
Authority: CN
Inventors: 上野骏
Original assignee: Meidensha Corp
Current assignee: Meidensha Corp
Priority date: 2019-08-23
Filing date: 2020-04-21
Publication date: 2022-08-12
Anticipated expiration: 2040-04-21
Also published as: JP2021035160A; CN114270663A; WO2021038956A1; JP6870708B2

Abstract

Torque ripple and electromagnetic exciting force which cause vibration and noise are further reduced. A pair of permanent magnet insertion holes are formed in a core (10) of a rotor (1), penetrate from one end face to the other end face of the core (10) in the same direction as a motor shaft (11) of the permanent magnet motor, and are arranged in an axisymmetric manner with respect to a d-axis of the rotor (1). Permanent magnet insertion holes are formed in a plurality of layers from the outer peripheral side to the axial center of the rotor (1). Magnetic isolation parts (17a, 17b) are formed in the pair of permanent magnet insertion holes (12a, 12b) formed closest to the outer peripheral side, and the magnetic isolation parts (17a, 17b) extend from the ends of the permanent magnet insertion holes (12a, 12b) on the q-axis side of the rotor (1) to the d-axis side along the outer periphery of the rotor (1) and penetrate through the iron core (10) from one end to the other end in the same direction as the motor shaft (11). The magnetic shielding sections (17a, 17b) are formed in a range of 14 DEG to 46 DEG in electrical angle from the d-axis.

Description

Rotor

Technical Field

The present invention relates to a motor for an electric vehicle (EV, HEV, PHEV, etc.), and more particularly to a rotor of a permanent magnet motor having a plurality of permanent magnets.

Background

Electric vehicles are desired to have low vibration and low noise. As a method for reducing noise in a motor in which a plurality of layers of permanent magnets are arranged, for example, a method is employed in which the width between the permanent magnets is equal to or greater than the opening width of the slots of the stator (patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 9-266646

Disclosure of Invention

However, in the above-described conventional method, suppression of the magnetic flux density is insufficient, and thus torque ripple and electromagnetic excitation force, which cause vibration and noise, cannot be sufficiently reduced.

In view of the above, an object of the present invention is to further reduce torque ripple and electromagnetic exciting force which cause vibration and noise.

In the rotor of the permanent magnet motor according to one aspect of the present invention, a pair of permanent magnet insertion holes are formed in a core of the rotor, the pair of permanent magnet insertion holes are arranged to penetrate in the same direction as a motor shaft of the permanent magnet motor from one end face to the other end face of the core and are arranged to be axisymmetrical with respect to a d-axis of the rotor, the pair of permanent magnet insertion holes are arranged in a plurality of layers from an outer peripheral side to an axial center of the rotor, a first magnetic blocking portion (japanese: magnetic radiation blocking portion) is formed in the pair of permanent magnet insertion holes closest to the outer peripheral side, the first magnetic blocking portion extends from an end of the pair of permanent magnet insertion holes on a q-axis side of the rotor to the d-axis side of the rotor and penetrates in the same direction as the motor shaft from one end to the other end of the core, the first magnetic partition is formed in a range of 14 to 46 degrees in electrical angle from the d-axis.

In the rotor according to an aspect of the present invention, a second magnetic shielding portion is formed on the q-axis side end portion of the pair of permanent magnet insertion holes formed on the axial center side of the pair of permanent magnet insertion holes on the outer peripheral side, and the second magnetic shielding portion forms a concentric arc centered on the d-axis upper and outer diameter side end portions of the rotor.

In one aspect of the present invention, the rotor is configured such that the length of the permanent magnet inserted into the permanent magnet insertion hole in the longitudinal direction of the cross section is longer as the rotor goes from the outer peripheral side to the axial center side.

In the rotor according to an aspect of the present invention, the permanent magnets inserted into the pair of permanent magnet insertion holes have a V-shaped arrangement angle that decreases from the outer peripheral side of the rotor toward the axial center side.

In one aspect of the present invention, the rotor is divided into a plurality of permanent magnets arranged on the axial center side, and the divided permanent magnets are concentrically arranged with the end portion of the rotor on the outer diameter side on the d-axis as the center.

With the present invention described above, the magnetic flux density is suppressed, and therefore, torque ripple and electromagnetic exciting force that cause vibration and noise are further reduced.

Drawings

Fig. 1 is a cross-sectional view of a rotor as one embodiment of the present invention, the cross-sectional view being perpendicular to an axial direction of the rotor.

Fig. 2 is a waveform diagram of a gap magnetic flux density of a conventional rotor having no magnetic cutoff portion.

Fig. 3 is a waveform diagram of the air gap flux density of the rotor of fig. 1 having magnetic partitions.

Fig. 4 is a characteristic diagram showing changes in harmonic components of the rotor of fig. 1.

Fig. 5 is a characteristic diagram showing a change in torque ripple of the rotor of fig. 1.

Fig. 6 is an enlarged view of a peripheral portion of the groove of fig. 1.

Fig. 7 is an explanatory diagram showing a range of the groove of fig. 6.

Fig. 8 is a cross-sectional view of a rotor as one embodiment of the present invention, the cross-sectional view being orthogonal to an axial direction of the rotor.

Fig. 9 is a cross-sectional view of a rotor as one embodiment of the present invention, the cross-sectional view being orthogonal to an axial direction of the rotor.

Fig. 10 is a cross-sectional view of the conventional rotor perpendicular to the axial direction.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment mode 1

Fig. 1 shows a structure of a cross section orthogonal to an axial direction of a rotor 1 of a permanent magnet motor as one embodiment of the present invention. In the figure, only one main pole of the rotor 1 is shown, and the other main poles have the same structure as the main pole, and thus are not shown.

The permanent magnet motor includes a rotor 1 and a stator 2 coaxially surrounding the rotor 1. A plurality of stator slots 22 to which the stator coils 21 are attached are formed in the stator 2 at equal intervals along the outer periphery of the rotor 1.

Iron core 10

The core 10 of the rotor 1 is a substantially cylindrical member formed by laminating silicon steel plates. A motor shaft 11 is fitted into the axial core of the core 10, and the motor shaft 11 is rotatably supported by a bearing (not shown).

An axis of the iron core 10 indicated by a straight line d in fig. 7 is a d-axis of d-q axis coordinates, and the straight line d connects the axial center of the rotor 1 (motor shaft 11) in fig. 1 and the center of an arbitrary main magnetic pole generating a magnet torque (for example, the center position between the pair of

permanent magnets

13a and 13b (15a and 15 b)). The core 10 between the

permanent magnets

13a and 13b (15a and 15b) of the main pole corresponding to one pole and the

permanent magnets

13a and 13b (15a and 15b) of the main pole adjacent to the main pole in the circumferential direction serves as an auxiliary magnetic pole portion 16 for generating a reactive torque (japanese patent No. リアクタンストルク). Further, an axis indicated by a straight line q in the drawing connecting the axial center of the rotor 1 (motor shaft 11) and the central axis of the auxiliary magnetic pole portion 16, that is, an axis orthogonal to the d-axis in an electrical angle is a q-axis of d-q axis coordinates.

Permanent

magnet insertion holes

12a, 12b, 14a, 14b

As shown in fig. 1, a pair of permanent magnet insertion holes are formed in a V-shape on the outer peripheral side and the axial center side of the rotor 1 in the main pole, and two layers of permanent magnets are arranged.

That is, a pair of permanent

magnet insertion holes

12a, 12b are formed on the outer peripheral side of the core 10 so as to penetrate the core 10 in the same direction as the motor shaft 11 from one end face to the other end face of the core 10. The permanent

magnet insertion holes

12a and 12b are arranged at equal intervals in the circumferential direction of the core 10.

Further, a pair of permanent

magnet insertion holes

14a, 14b are formed to penetrate the core 10 at positions closer to the axial center side of the rotor 1 than the permanent

magnet insertion holes

12a, 12b, in the same manner as the permanent

magnet insertion holes

12a, 12 b. In particular, the permanent

magnet insertion holes

14a, 14b are formed longer in diameter than the permanent

magnet insertion holes

12a, 12 b. The permanent

magnet insertion holes

12a and 12b are also arranged at equal intervals in the circumferential direction of the core 10.

The permanent

magnet insertion holes

12a, 12b, 14a, 14b are arranged in a V-shape that is axisymmetrical with respect to the d-axis of the rotor 1 and has an arrangement angle that increases as the rotor 1 approaches the outer periphery. In particular, the arrangement angle of the V-shape of the permanent

magnet insertion holes

14a, 14b on the axial center side is set smaller than that of the permanent

magnet insertion holes

12a, 12b on the outer peripheral side.

Permanent magnets

13a, 13b, 15a, 15b

Permanent magnets

13a, 13b in the form of long plates extending in the axial direction of the rotor 1 are inserted into the permanent

magnet insertion holes

12a, 12b, and the pair of

permanent magnets

13a, 13b are arranged in a V-shape in the circumferential direction of the core 10.

On the other hand,

permanent magnets

15a and 15b in the form of long plates extending in the axial direction of the rotor 1 are inserted into the permanent

magnet insertion holes

14a and 14b, and the pair of

permanent magnets

15a and 15b are arranged in a V-shape on the axial center side of the core 10. In particular, as shown in fig. 1, the length L2 in the longitudinal direction of the cross section of the

permanent magnets

15a, 15b is set to be longer than the length L1 in the longitudinal direction of the cross section of the

permanent magnets

13a, 13 b.

As described above, the pair of permanent magnets are arranged in a two-layer structure in the rotor 1. In particular, in this embodiment, the outer peripheral magnetic pole faces 13ou and 15ou of the

permanent magnets

13a, 13b, 15a, and 15b shown in fig. 7 have the same magnetic polarity (S pole or N pole). Thereby, one main magnetic pole is formed by the

permanent magnets

13a, 13b, 15a, 15 b.

Magnetic shielding parts

17a, 17b

As shown in fig. 1 and 6, a magnetic shielding portion 17a (first magnetic shielding portion) is formed at the q-axis side end of the permanent magnet insertion hole 12a, and the magnetic shielding portion 17a extends in the outer circumferential direction toward the d-axis side and penetrates in the same direction as the motor shaft 11 from one end to the other end of the core 10.

Similarly, a magnetic shielding portion 17b (first magnetic shielding portion) is formed at the q-axis end of the permanent magnet insertion hole 12b, and the magnetic shielding portion 17b is axially symmetric to the magnetic shielding portion 17a about the d-axis, extends toward the d-axis side along the outer periphery, and penetrates in the same direction as the motor shaft 11 from one end to the other end of the core 10.

In particular, the

magnetic shielding portions

17a and 17b are formed so as to limit the electrical angle a from the d-axis shown in fig. 7 to a range of 14 ° to 46 °. Since the

magnetic shielding portions

17a and 17b are holes (spaces), the magnetic permeability is smaller than that of the core 10, and the magnetic flux hardly passes through them, thereby functioning as a magnetic shielding portion. The

magnetic shielding portions

17a and 17b are formed by filling holes (spaces) formed therein with nonmagnetic metal (e.g., aluminum, brass, etc.), adhesive, varnish, resin, or the like having low magnetic permeability.

Effects of the present embodiment

With the above-described structure of the rotor 1, the

magnetic shielding portions

17a and 17b are formed between the d-axis and the q-axis of the rotor 1, and thus, the change in the magnetic flux density distribution generated on the outer peripheral surface of the rotor 1 by the

permanent magnets

13a and 13b, particularly the magnetic flux density distribution at both end portions in the circumferential direction of the main magnetic pole, can be made close to a sine wave. This effectively reduces the torque ripple and the electromagnetic exciting force of the rotor 1, and further reduces the noise and vibration of the permanent magnet motor.

In particular, since the

magnetic shielding portions

17a and 17b are formed so as to be restricted to the range of 14 ° to 46 ° in electrical angle a from the d-axis, the magnetic flux of the magnet of the rotor 1 in this range is suppressed, and therefore, the magnetic flux density distribution on the circumference of the gap (japanese: ギャップ) between the outer periphery of the rotor 1 and the

magnetic shielding portions

17a and 17b approaches a sine wave shape. Therefore, the torque ripple and the electromagnetic excitation force are reduced, and the vibration and the noise can be further reduced. Further, by setting the electrical angle a to be equal to or smaller than a range of about 46 ° (for example, a range of the first and second stator slots 22 from the d-axis shown in fig. 6), the magnetic flux amount of the second teeth 23 from the magnetic pole center (d-axis) is suppressed, and the magnetic path width is also ensured, so that the torque is also improved. Further, the 13 th harmonic of the radial component of the magnetic flux density distribution is also suppressed.

Fig. 2 shows waveforms of the air gap magnetic flux density of the conventional rotor 1 shown in fig. 10 without the

magnetic shielding portions

17a and 17 b. Fig. 3 shows a waveform of the air gap magnetic flux density of the rotor 1 having the

magnetic shielding portions

17a and 17 b. In particular, the characteristic diagram of fig. 3 shows the waveform of the void magnetic flux density when the electrical angle a from the d-axis to the d-axis side end of the magnetic cutoff portion 17a is 16 °. As is clear from comparison of the characteristic diagrams of fig. 2 and 3, with respect to the air gap magnetic flux density, the magnetic flux density decreases approximately in a sine wave shape before and after the electrical angle a of 60 ° and 120 °. This tendency is particularly remarkable when the electrical angle a of the

magnetic shielding portions

17a and 17b from the d-axis is in the range of 14 ° to 46 °.

Fig. 4 shows the change of the electric angle a to the d-axis end of the rotor 1 and the harmonic component of the gap magnetic flux density waveform, and fig. 5 shows the change of the torque ripple of the rotor 1 (the standard is that the electric angle a is 28 °). As can be seen by comparing the graphs of fig. 4 and 5, the torque ripple is similar to the waveform of the 13 th harmonic. This suggests that: by providing the

magnetic shielding portions

17a and 17b, the 13 th harmonic is suppressed, and the torque ripple is reduced. And displays: when the electrical angle a is too small, the 13 th harmonic tends to increase, and the range in which the 13 th harmonic can be reduced is more preferably 14 ° or more and a <28 °.

Even if the magnetic shielding portion of the present invention has a three-layer structure, for example, as described later, having two or more layers, the same tendency as described above is satisfied as long as the magnetic shielding portion closest to the outer peripheral side is within the same range as described above. The arrangement of the

permanent magnets

13a, 13b, 15a, and 15b is not limited to the arrangement of the "V" described above, and similar effects can be obtained even in the case of the "inverted V", "U", "arch", "trapezoid", and the like.

Embodiment mode 2

In the rotor 1 of embodiment 2 illustrated in fig. 8,

magnetic shielding portions

18a, 18b, 32a, and 32b (second magnetic shielding portions) are formed on the q-axis side of the pair of permanent magnets arranged in multiple layers on the axial center side of the pair of

permanent magnets

13a and 13b closest to the outer peripheral side, and the

magnetic shielding portions

18a, 18b, 32a, and 32b form concentric arcs centered on the outer diameter side end E on the d-axis of the rotor 1.

In the illustrated form, the pair of permanent magnets are arranged in three layers. That is, the permanent

magnet insertion holes

12a and 12b, the permanent

magnet insertion holes

14a and 14b, and the permanent

magnet insertion holes

30a and 30b are arranged in this order from the outer peripheral side to the axial center of the rotor 1, and are formed in a V-shape that is axisymmetrical with respect to the d-axis of the rotor 1 and has an arrangement angle that increases as it approaches the outer periphery of the rotor 1. The permanent

magnet insertion holes

30a and 30b are formed in circular arcs longer than the permanent

magnet insertion holes

14a and 14 b.

Then, the

permanent magnets

13a, 13b, the

permanent magnets

15a, 15b, and the

permanent magnets

31a, 31b are inserted into the permanent

magnet insertion holes

12a, 12b, the permanent

magnet insertion holes

14a, 14b, and the permanent

magnet insertion holes

30a, 30b, respectively, whereby the pair of

permanent magnets

13a, 13b, 15a, 15b, 31a, 31b are arranged in a V-shape on the axial center side. As shown in fig. 8, the length L3 in the longitudinal direction of the cross section of

permanent magnets

31a and 31b is set to be longer than the length L2 in the longitudinal direction of the cross section of

permanent magnets

15a and 15 b. As described above, the pair of permanent magnets are arranged in the rotor 1 in a three-layer structure.

Magnetic shielding portions

18a and 18b are formed at the q-axis side end portions of the permanent

magnet insertion holes

14a and 14b, and the

magnetic shielding portions

18a and 18b extend in concentric arcs around the d-axis upper outer diameter side end portion E of the rotor 1 and penetrate in the same direction as the motor shaft 11 from one end to the other end of the core 10.

Similarly,

magnetic shielding portions

32a and 32b are formed at the q-axis side end portions of the permanent

magnet insertion holes

30a and 30b, and the

magnetic shielding portions

32a and 32b extend in concentric arcs around the d-axis upper outer diameter side end portion E of the rotor 1 and penetrate in the same direction as the motor shaft 11 from one end to the other end of the core 10.

In addition to the effects of embodiment 1, the structure of the rotor 1 according to this embodiment is also expected to have the effects of improving torque and reducing loss because the

magnetic shielding portions

18a, 18b, 32a, and 32b are formed in concentric arcs, and therefore, the flow of magnetic flux is smoother than in the case of the linear shielding portions. In particular, by setting the d-axis end of the rotor 1 to the center of the arc, the permanent magnet can be embedded further on the inner diameter side of the rotor 1 while securing the magnetic path width, and therefore the loss of the magnet can be reduced.

As shown in the figure, the lengths L1, L2, and L3 in the longitudinal direction of the cross section of the

permanent magnets

13a, 13b, 15a, 15b, 31a, and 31b are increased from the outer peripheral side to the axial center side of the rotor 1, thereby further increasing the magnet torque of the rotor 1.

As shown in the figure, the arrangement angle of the pair of

permanent magnets

13a, 13b, 15a, 15b, 31a, 31b arranged in the V shape decreases from the outer peripheral side of the rotor 1 toward the axial center side, and the distance between the pair of permanent magnets on the d-axis side of each layer gradually increases. This suppresses magnetic saturation occurring between the layers, thereby improving the reactive torque.

As shown in the structure of the rotor 1 illustrated in fig. 9, the following may be employed: the permanent magnets 15 disposed on the axial center side of the rotor 1 are divided into a plurality of (for example, 3 or more), and the permanent magnets 15 are concentrically disposed with the outer diameter side end E of the d-axis of the rotor 1 as the center. The permanent magnet 15 on the axial side is inserted into a permanent magnet insertion hole 14 concentrically arranged in an arc around the end E on the outer diameter side of the d-axis of the rotor 1. In this embodiment, the plurality of permanent magnets 15 are concentrically arranged as described above, and the eddy current loss of the permanent magnets 15 is further reduced. The arrangement of the plurality of permanent magnets arranged in each layer is closer to a U shape from the outer peripheral side of the rotor 1 toward the axial center side, so that the flow of the magnetic flux is smooth and the reactive torque is further improved.

Description of the reference numerals

1. A rotor; 2. a stator; 10. an iron core; 11. a motor shaft; 12a, 12b, 14a, 14b, 30a, 30b, permanent magnet insertion holes; 13a, 13b, 15a, 15b, 31a, 31b, a permanent magnet; 16. an auxiliary magnetic pole portion; 17a, 17b, 18a, 18b, 32a, 32b, magnetic cut-off; 21. a stator coil; 22. a stator slot; 23. and (4) teeth.

Claims

1. A rotor, which is a rotor of a permanent magnet motor, characterized in that,

a pair of permanent magnet insertion holes are formed in the core of the rotor, penetrate through the core from one end face to the other end face in the same direction as a motor shaft of the permanent magnet motor, and are arranged in a V shape axially symmetrical to a d axis of the rotor,

the pair of permanent magnet insertion holes formed in multiple layers are arranged from the outer peripheral side of the rotor to the axial center,

a first magnetic isolation part is formed in the pair of permanent magnet insertion holes closest to the outer peripheral side, extends from the end of the pair of permanent magnet insertion holes on the q-axis side of the rotor to the d-axis side along the outer periphery of the rotor, and penetrates through the iron core from one end to the other end in the same direction as the motor shaft,

the first magnetic partition is formed in a range of 14 DEG or more and less than 28 DEG in electrical angle from the d-axis,

a second magnetic shielding portion that forms a concentric arc with the end portion on the outer diameter side of the d-axis of the rotor is further formed at the q-axis side end portion of the pair of permanent magnet insertion holes formed at positions closer to the axial center side than the pair of permanent magnet insertion holes on the outer peripheral side.

2. The rotor of claim 1,

the permanent magnets inserted into the permanent magnet insertion holes have longer lengths in the longitudinal direction of the cross section as they go from the outer peripheral side of the rotor toward the axial center side.

3. The rotor of claim 1 or 2,

the arrangement angle of the permanent magnets inserted into the pair of permanent magnet insertion holes becomes smaller as going from the outer peripheral side of the rotor toward the axial center side.

4. The rotor of claim 1 or 2,

the permanent magnet disposed on the axial center side is divided into a plurality of pieces, and the divided permanent magnets are concentrically disposed with the outer diameter side end portion on the d-axis of the rotor as the center.