JP2005045984A - Rotor for permanent magnet synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor that allows omission of the post-cutting process after sticking magnets, to obtain high magnetic flux density, and to produce high torque density. <P>SOLUTION: This rotor for a permanent magnet synchronous motor has a rotating shaft, a rotor core, and a plurality of magnetic poles fixed on the outside circumference surface of the rotor core. The magnetic poles are divided into a plurality of permanent magnets per pole, and the magnets are arranged, in such a way that the magnetization direction of each permanent magnet concentrates at magnetic pole center, which is what is called Halbach magnet arrangement. In this rotor, when magnets arranged at the center of the Halbach magnet arrangement constituting one pole are designated as main magnets and other magnets as auxiliary magnets, the thickness of the auxiliary magnets is made smaller than those of the main magnets. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a so-called permanent magnet type synchronous motor, and more particularly to the structure of the rotor.

As a conventional technique, there is a magnet arrangement of a rotor of a permanent magnet type synchronous motor as shown in FIG. FIG. 2 shows an example of a radially oriented magnet arrangement.
In the figure, the rotor 20 has an even number of rotor cores 22 around the rotating shaft 21 and permanent magnets 23 around the rotor core 21 (six cases are shown in the figure), and the directions of the magnetic poles are alternately reversed. It is arranged on the circumferential surface.
According to this configuration, although the manufacturing is simple and the cost is reduced, it is difficult to obtain a high magnetic flux density. Therefore, it is not very effective for increasing the torque of the motor.

  On the other hand, so-called Halbach magnet arrangements have been proposed as solutions to the drawbacks of this radially oriented magnet arrangement (see, for example, Non-Patent Document 1 and Patent Documents 1 to 3).

Ohashi, “Application of Rare Earth Magnets”, New Magnetic Materials Seminar, November 16, 2001, pp. 63-66 Japanese Patent Laid-Open No. 5-101956 Japanese Patent Laid-Open No. 2003-124019 Japanese Patent Laid-Open No. 10-191585

FIG. 3 is a cross-sectional view of an example of a rotor of a synchronous motor similar to the Halbach magnet arrangement described in Non-Patent Document 1.
In FIG. 3, 30 is a rotor, 31 is a rotating shaft, and 32 is a rotor core. Reference numeral 33 denotes a magnetic pole for one pole, and here a main magnet (permanent magnet) 34 and three auxiliary magnets (permanent magnet) 34 'form one pole. Therefore, here is a Halbach magnet arrangement in which the number of magnetic poles is 6 poles and the number of divisions of 1 pole is 4. Arrows 35 and 35 ′ drawn in each permanent magnet 34 indicate the magnetization direction of each permanent magnet. 35 indicates the magnetization direction of the main magnet whose magnetization direction is perpendicular, and 35 'indicates the magnetization direction of the auxiliary magnet whose magnetization direction is other than perpendicular.
In this way, the Halbach magnet arrangement is divided into a plurality of permanent magnets per pole, and the permanent magnets are arranged so that the magnetic flux is concentrated at the center of the magnetic pole by changing the magnetization direction 35 'of each permanent magnet little by little. Therefore, a high magnetic flux density can be obtained, which is extremely effective for increasing the torque of the motor. Usually, 2 to 5 divisions are used per pole.

4 is a cross-sectional view showing an example of a synchronous motor using the Halbach magnet array rotor of FIG. In the figure, 30 is a Halbach magnet array rotor, 31 is a rotating shaft, 32 is a rotor core, 33 is a permanent magnet, 40 is a stator, 41 is a stator core, 41a is a tooth, and 42 is a stator winding. It is. The stator core 42 is formed by laminating a large number of thin plate materials such as silicon steel plates, and the inside of the stator 40 is a radial tooth 42a, and the insulation coated electric wires 42 are wound around the teeth 42a. . In the central space of the stator 40, the rotor 30 of FIG. 3 in which the permanent magnets 34 are arranged on the surface of the Halbach magnet is arranged. Therefore, a rotating magnetic field is generated by passing a three-phase alternating current through the stator winding 32, and the rotor 30 is rotated.
The rotor 30 of the synchronous motor having such a Halbach magnet arrangement can obtain a higher magnetic flux density and is extremely effective in increasing the torque of the motor as compared with a radially oriented magnet arrangement.

FIG. 5 also shows an example of the Halbach magnet arrangement. Here, an example in which the number of magnetic poles is 8 poles and the number of divisions of 1 pole is 1 is shown.
In the figure, 50 is a rotor, 51 is a rotating shaft, and 52 is a rotor core. 53 is a magnetic pole for one pole, and here, one main magnet (permanent magnet) 54 and one auxiliary magnet (permanent magnet) 54 'form one pole. Arrows 55 and 55 'drawn in the magnets 54 and 54' indicate the magnetization directions of the magnets 54 and 54 ', respectively.
In this case, the thickness H1 of the main magnet 54 and the thickness H2 of the auxiliary magnet 54 ′ are set to be equal to each other (H1 = H2), and the main magnet 541 and the auxiliary magnet 54 ′ are arranged with no gap therebetween. The same can be said for the rotor of the Halbach magnet arrangement shown in FIG.

However, in the rotor using the conventional Halbach magnet arrangement, since a plurality of magnets are pasted, there is a step between the main magnet and the auxiliary magnet due to variation in pasting work, shape error in the thickness or width of the magnet, and the like. There was a problem that unevenness was likely to occur on the magnet surface.
Since the step generated when the magnet is attached causes distortion in the magnetic flux distribution on the magnet surface, there is a problem in that the motor characteristics are adversely affected.
For this reason, there has been a problem that it is necessary to perform cutting after attaching the magnet so as to eliminate the step on the surface of the magnet and prevent distortion of the magnetic flux density.
The present invention has been made in view of such problems, and provides a permanent magnet type synchronous motor using a Halbach magnet arrangement that can obtain a good magnetic flux density distribution by omitting the cutting process after magnet attachment. The purpose is to do.

In order to solve the above problem, the invention described in claim 1 has a rotating shaft, a rotor iron core, and a plurality of magnetic poles fixed to the outer peripheral surface of the rotor iron core. A permanent magnet type synchronous motor rotor having a magnet array arranged so that the magnetization direction of each permanent magnet is concentrated at the center of the magnetic pole, that is, a so-called Halbach magnet array, constitutes one pole. The magnet arranged at the center of the Halbach magnet arrangement is a main magnet, the other is a supplementary magnet, the thickness of the main magnet is H1, and the thickness of the supplementary magnet is H2. It is.
As described above, since the thickness of the auxiliary magnet is set to be smaller than the thickness of the main magnet in advance, a step at the time of magnet attachment can be absorbed, so that a post-cutting process at the time of manufacturing the rotor can be omitted.
The invention of a permanent magnet type synchronous motor according to claim 2 comprises: a stator comprising an annular stator core including a tooth extending radially from a central portion; and a winding wound around the tooth; The rotor according to claim 1, which is disposed in a central space formed at the tip of the rotor.
In this way, since the rotor having a thickness of the auxiliary magnet smaller than that of the main magnet is used, the cutting process can be omitted, and therefore a high-performance synchronous motor can be provided without processing after magnet assembly.

As described above, according to the present invention, a rotating shaft, a rotor core, and a plurality of magnetic poles fixed to the outer peripheral surface of the rotor core are provided, and the magnetic poles have a plurality of permanent magnets per pole. In a permanent magnet type synchronous motor rotor provided with a magnet array arranged so that the magnetization direction of each permanent magnet is concentrated at the center of the magnetic pole, that is, a so-called Halbach magnet array, a Halbach magnet constituting one pole When the magnet arranged at the center of the array is the main magnet and the other is the auxiliary magnet, the thickness of the auxiliary magnet is set to be smaller than the thickness of the main magnet, so that the step when the magnet is attached can be absorbed. There is an effect that the process can be omitted.
Moreover, since the distortion of the magnetic flux distribution on the magnet surface can be suppressed, a high-performance permanent magnet type synchronous motor can be provided.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view of a rotor according to the present invention.
In the figure, 10 is a rotor according to the present invention, 11 is a rotating shaft, and 12 is a rotor core. Reference numeral 13 denotes a magnetic pole for one pole. Here, one main magnet (permanent magnet) 14 and one auxiliary magnet (permanent magnet) 14 'form one pole. Arrows 15 and 15 'drawn in the magnets 14 and 14' indicate the magnetization directions of the magnets 14 and 14 ', respectively. The main magnet 15 and the auxiliary magnet 15 ′ are attached on the rotating shaft 11 by bonding or the like. Reference numeral 4 denotes the magnetization direction of the magnet, which is a so-called Halbach magnet arrangement structure. The thickness H2 of the auxiliary magnet 15 ′ is smaller than the thickness H1 of the main magnet 15 (H1> H2).
The thickness H2 of the auxiliary magnet and the thickness H1 of the main magnet are set so that the magnetic flux density distribution on the magnet surface is a sine wave. Further, the thickness H2 of the auxiliary magnet can be determined from an analysis result by a finite element method or the like.
Thus, by setting the thickness H2 of the auxiliary magnet 15 ′ to be smaller than the thickness H1 of the main magnet 15 in advance, the step at the time of attaching the magnet can be absorbed, so that the post-cutting step can be omitted.

It is sectional drawing of the rotor which concerns on this invention. An example of the magnet arrangement of the radial orientation of the rotor which concerns on a prior art is shown. An example of the Halbach magnet arrangement according to the prior art is shown. It is a cross-sectional view which shows an example of the synchronous motor using the Halbach magnet arrangement | sequence rotor of FIG. Similarly, in the example of the Halbach magnet arrangement, an example in which the number of magnetic poles is 8 poles and the number of divisions of 1 pole is 1 is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotor which concerns on this invention 11 Rotating shaft 12 Rotor core 13 Magnetic pole for 1 pole 14 Main magnet 14 'Supplementary magnet 15, 15' Magnetization direction H1 Main magnet thickness H2 Thickness of supplementary magnet

Claims (2)

A rotating shaft, a rotor core, and a plurality of magnetic poles fixed to the outer peripheral surface of the rotor core, the magnetic poles being divided into a plurality of permanent magnets per pole, and the magnetization direction of each permanent magnet In a rotor of a permanent magnet type synchronous motor having a magnet arrangement arranged so as to concentrate on the magnetic pole center, so-called Halbach magnet arrangement,
When the magnet arranged at the center of the Halbach magnet array constituting one pole is the main magnet, the other is the auxiliary magnet, the thickness of the main magnet is H1, and the thickness of the auxiliary magnet is H2,
H1> H2
A rotor of a permanent magnet type synchronous motor characterized by the above. A stator consisting of an annular stator core containing radially extending teeth spaced apart from the center, and windings wound around the teeth;
A permanent magnet type synchronous motor comprising: the rotor according to claim 1 disposed in a central space formed at a tip of the teeth.

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