JPS63129835A - Permanent-magnet rotor for rotary electric machine - Google Patents

Abstract

PURPOSE:To enhance the working efficiency of permanent magnet material and improve characteristic and miniaturize a device and reduce the cost, by composing both the sides of a field pole in the peripheral direction, of the permanent magnet material of a coercive fore greater than that on the center of the field pole. CONSTITUTION:So far as permanent magnets 14 at both the ends of a field pole 13 are concerned, the residual magnetic flux density Br is equal to that of a central permanent magnet 15 and the coercive force is set to be great. Accordingly, surface magnetic-flux density B1 is uniformed over all the sphere of the field pole 13 in the peripheral direction, and the demagnetization curve is trapezoidal-wave-distributed. However, demagnetization-resisting quantity is Hd1 at the central permanent magnet 15, but at the permanent magnets 14 on both the sides, the quantity is Hd2 which is greater than Hd1. Accordingly, even if a great demagnetizing field is worked at both the side sections of the field pole 13 with armature reaction, the demagnetization- resisting quantity Hd2 at the sections is great and so the characteristic of a rotary electric machine can be improved by the component. Otherwise, if the demagnetization- resisting quantity Hd2 of the permanent magnets 14 is set to be equal to a conventional one, the using quantity of permanent magnet material is reduced by the component.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a permanent magnet rotor for a rotating electric machine in which field magnetic poles provided opposite to an armature are made of permanent magnets.

(Prior Art) An example of a permanent magnet rotor of rotating field type is shown in FIG. Here, 1 is the rotor yoke, 2 is the permanent magnet (
The field magnetic pole 1 is made entirely of a homogeneous permanent magnet material and has a constant thickness over the entire circumferential area. The surface magnetic flux density B1 of this permanent magnet 2 is determined by the demagnetization curve (second quadrant of the B-H curve) of this permanent magnet material shown in FIG. 8 and the permeance coefficient p, assuming that the thickness dimension is C1 and the air gap length is g. It is determined from the intersection Q with the straight line P whose slope is cape (/g), and the air gap magnetic flux distribution at that time is as shown in Fig. 9. Also, the demagnetization resistance mH of the permanent magnet 2 in this case
d1 is the H component (
Hd 1). In the shape of the permanent magnet 2 shown in FIG. 7, since the thickness dimension i is constant, the demagnetization resistance Hd1 of each part is uniform.

However, since the armature reaction generated when a load current flows through the armature coil reaches its maximum value on the horizontal axis, that is, between the poles, a strong demagnetizing field is generated on both sides of the permanent magnet 2 in the circumferential direction. . For this reason, in conventional permanent magnet rotors,
Considering the demagnetization resistance on both sides in the circumferential direction of the permanent magnet 2, it is necessary to use a large amount of permanent magnet material while leaving a margin for the demagnetization resistance in the center. There was a problem with low efficiency. This impedes the downsizing of rotating electric machines and becomes a factor that significantly increases manufacturing costs, especially when expensive permanent magnet materials such as rare earth magnets are used.

In addition, in order to revise the air gap magnetic flux density distribution, both sides of the permanent magnet 2 in the circumferential direction are processed into a sloped shape as shown in FIG.
As shown in FIG. 11, the curvature of the outer circumference may be made different from the curvature of the inner circumference of the armature. In this case, the thickness dimension C1 and the gap length g1 at the center of the permanent magnet 2,
Since the thickness/At2 and the gap length g2 are different at both ends, the gap magnetic flux density distribution approaches a sine wave as shown in Figure 12, or the demagnetization resistance becomes H at the center as shown in Figure 11.
d 1 becomes Hd2 at both ends, and the demagnetization resistance at both ends becomes smaller than that at the center.

Therefore, in order to cope with the armature reaction, the amount of permanent magnet material used increases further, resulting in a problem that usage efficiency further decreases.

(Problems to be Solved by the Invention) As stated above, in the conventional permanent magnet field, it is not possible to sufficiently improve the usage efficiency of the permanent magnet material due to the armature reaction. This resulted in problems such as an increase in size and cost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a permanent magnet rotor for a rotating electric machine that can improve the efficiency of using permanent magnet materials.

[Structure of the Invention] (Means for Solving the Problems) In the permanent magnet rotor of a rotating electric machine according to the present invention, the permanent magnets forming each part of the field magnetic poles are arranged so that both sides in the circumferential direction are located closer to the center. It is characterized by being made of a permanent magnetic material with a large coercive force.

(Function) Since the coercive force on both circumferential sides of each permanent magnet forming each part of the field magnetic pole is larger than that at the center, the maximum value of the armature reaction exists between the poles. A large amount of demagnetization resistance can be ensured.

(Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

11 is an armature, 12 is a rotor yoke provided within the armature 11, and 13 is one field magnetic pole.

This field magnetic pole 13 is constructed by integrally connecting three permanent magnets in the circumferential direction, and each has the same thickness dimension. Both permanent magnets 14 located on both sides in the circumferential direction have the same characteristics, but are set to have different characteristics from the permanent magnet 15 in the center. That is, the permanent magnets 14 located at both ends
The residual magnetic flux density is the same as that of the central permanent magnet 15, and the coercive force is larger than that of the central permanent magnet 15.

FIG. 2 shows the demagnetization curves of each of the permanent magnets 14 and 15. Here, the demagnetization curve of the permanent magnet 15 located at the center is drawn as a solid line, and the demagnetization curve of the permanent magnet 14 located at both ends is drawn as a broken line, but the line between point Q1 and point B is a solid line. As is clear from FIG. 2, since the residual magnetic flux densities Br of both permanent magnets 14 and 15 are selected to be equal, the surface magnetic flux density B1 is the same in the entire circumferential direction of the field magnetic pole 13. It is almost the same as the conventional example shown in FIG. The permanent magnet 1 on both sides is Hdl.
4, Hd2 becomes larger than Hd. Therefore, even if there is a situation where a large demagnetizing field acts on both sides of the field magnetic pole 13 due to armature reaction, the demagnetization resistance m Hd 2 of that part can be increased as described above, and the rotating electric machine can contribute to improving the characteristics of Alternatively, if the demagnetization resistance QHd 2 on both sides is set to be the same as the conventional one, the amount of permanent magnet field used can be reduced accordingly, and the rotating electric machine can be downsized and cost reduced.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. The difference from the first embodiment is that the field magnetic pole 13
By setting the curvature of the outer circumferential surface of the armature 11 to be larger than the curvature of the inner circumferential surface of the armature 11 and aligning the center of each circumferential surface with the center of the
The point is that the gap length between 1 and 1 is increased. The field magnetic pole 13 is composed of three permanent magnets connected in the circumferential direction, and the permanent magnets 15 on both sides have the same residual magnetic flux density Br as the central permanent magnet 14, and have a large coercive force. This is the same as the first embodiment.

The demagnetization curve in this case is as shown in FIG.

Here, too, the demagnetization curve of the permanent magnet 15 located at the center is drawn with a solid line, and the demagnetization curve of the permanent magnet 14 located at both ends is drawn with a broken line. When the surface magnetic flux density and demagnetization resistance of each part of the field magnetic pole 13 are determined based on FIG. 4 in the same manner as explained in the conventional example, the surface magnetic flux density B2 of the permanent magnets 14 on both sides is Magnetic flux density B
, it is clear that the air gap magnetic flux density distribution becomes close to a sine wave. Further, the demagnetization resistance giHd2 of the permanent magnets 15 on both sides is greater than that of the conventional example shown in FIG. Therefore, even with this (1) configuration, the same effects as in the first embodiment can be achieved.

Next, a third embodiment of the present invention will be described with reference to FIGS. 5 and 6. The structure of the field magnetic pole 13 is as shown in FIG.
Although it is the same as the embodiment, the permanent magnet materials are selected so that the permanent magnets 14 on both sides have a larger coercive force and a smaller residual magnetic flux density than the permanent magnet 15 in the center. In this case, the demagnetization curve of the central permanent magnet 15 is shown by a solid line, and the demagnetization curve of the permanent magnets 14 on both sides is shown by a broken line. In the figure, when the surface magnetic flux density and demagnetization resistance of each part of the field magnetic pole 13 are determined in the same way as explained in the conventional example, the surface magnetic flux density B1 of the permanent magnets 14 on both sides is the same as the table ID of the central permanent magnet 15.
&! Since the i flux density is smaller than B1, the air gap magnetic flux density distribution becomes close to a sine wave distribution as shown in FIG. 6, and it is clear that this is effective for waveform secretion. Furthermore, since the demagnetization resistance Q Hd 2 of the permanent magnets 14 on both sides is larger than the demagnetization resistance uHd 1 of the central permanent magnet 15, a large demagnetization field acts on both sides of the field magnetic pole 13 due to the armature reaction. Accordingly, it is possible to improve the usage efficiency of the permanent magnet material and to reduce the size and cost of the rotating electric machine.

[Effects of the Invention] As explained above, the present invention is applicable to KAI@, il! Both sides of the pole in the circumferential direction are made of permanent magnetic material with a larger coercive force than the center (1
By doing so, it is possible to improve the efficiency of use of the permanent magnet material, thereby achieving an excellent effect of improving the characteristics of the rotating electric machine, making it more compact, and reducing the cost.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a partial cross-sectional view of a rotating electrical machine, FIG. 2 is a demagnetization characteristic diagram of a permanent magnet, and FIGS. 3 and 4 are a diagram of the present invention. A first example showing a second embodiment of the invention
Figures and figures corresponding to Figure 2, Sasa Figures 5 and 6 are the third figures of the present invention.
An example is shown, FIG. 5 is a demagnetization characteristic diagram of a permanent magnet, FIG. 6 is an air gap magnetic flux density distribution diagram, FIGS. 7 to 13 are conventional examples, and FIG. 7 is a partial sectional view of a rotating electric machine. , Figure 8 is a permanent magnet demagnetization characteristic diagram, Figure 9 is an air gap magnetic flux density distribution diagram, and Figure 1
Fig. 0 and Fig. 11 are partial vertical cross-sectional views of rotating electric machines showing other conventional examples, respectively, Fig. 12 is a demagnetization characteristic diagram of the permanent magnet in Figs. 10 and 11, and Fig. 13 is the same air gap magnetic flux. It is a density distribution map. In the drawing, 11 is an armature, 13 is a field magnetic pole, and 14° and 15 are permanent magnets.

Claims (1)

[Claims] 1. Where the field magnetic poles provided facing the armature are made of permanent magnets, both sides in the circumferential direction of each pole of the field magnetic poles are made of a permanent magnet material having a larger coercive force than the center. A permanent magnet rotor for a rotating electrical machine characterized by