WO2015186280A1

WO2015186280A1 - Permanent magnet-embedded electric motor

Info

Publication number: WO2015186280A1
Application number: PCT/JP2015/001179
Authority: WO
Inventors: 河村　清美
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2014-06-02
Filing date: 2015-03-05
Publication date: 2015-12-10

Abstract

This permanent magnet-embedded electric motor is equipped with: a stator having windings that are wound around a stator core; and a rotor that is rotatably disposed with a gap from the inner circumferential surface of the stator. The rotor has a rotor core that has first magnet-embedding holes disposed on a q-axis and second magnet-embedding holes disposed on a d-axis, first permanent magnets that are inserted in the first magnet-embedding holes, and second permanent magnets that are inserted in the second magnet-embedding holes. The rotor core is constructed by stacking multiple thin iron plates, wherein the plate thickness of an inner diameter bridge section of a thin iron plate is smaller than the plate thickness of the thin iron plate, said inner diameter bridge section being an area surrounded by the short side of the first magnet-embedding hole on the inner circumferential side and short sides of two second magnet-embedding holes facing the aforementioned short side.

Description

Permanent magnet embedded motor

The present invention relates to an embedded permanent magnet electric motor having an embedded permanent magnet rotor configured by embedding a plurality of permanent magnets at predetermined intervals in a rotor core.

In such a technical field, conventionally, for example, a technique as described in Patent Document 1 is known. In the rotor disclosed in Patent Document 1, a first permanent magnet having a rectangular cross section in the radial direction of the rotor is separated from the outer periphery and embedded along the q-axis, and the center is disposed between the first permanent magnets. A second permanent magnet having a rectangular cross-section with a long side perpendicular to the d-axis is embedded on the side. A triangular flux barrier hole is formed between the first permanent magnet and the second permanent magnet.

In the conventional configuration described above, flux barrier holes for suppressing leakage magnetic flux are formed in the first magnet embedded hole and the second magnet embedded hole. However, when the flux barrier hole is provided, there is a limit to lengthening the magnet, and it is difficult to sufficiently secure the generated magnetic flux.

In addition, the iron core between the first permanent magnet and the second permanent magnet holds the rotor core on the inner diameter side and the outer diameter side. For this reason, in order to ensure the strength, the width of the iron core of the connecting portion has to be increased, which has been a factor in increasing the leakage magnetic flux.

JP 2001-333553 A

The embedded permanent magnet electric motor of the present invention has the following configuration. That is, a stator having a winding wound around a stator iron core and a rotor provided rotatably via an inner peripheral surface of the stator and a gap are provided.

The rotor includes a rotor core having a first magnet embedded hole provided on the q axis and a second magnet embedded hole provided on the d axis, and a first permanent magnet inserted into the first magnet embedded hole. And a second permanent magnet inserted into the second magnet embedding hole.

The rotor core is formed by laminating a plurality of thin steel plates, and in the thin steel plate, the short side of the inner circumference side of the first magnet embedded hole and the short sides of the two second magnet embedded holes facing the short side The plate | board thickness of the internal-diameter bridge part which is the area | region enclosed by is characterized by being smaller than the plate | board thickness of a thin steel plate.

The magnetic flux generated from the first permanent magnet flows through the inner diameter bridge portion to the reverse magnetic pole side of the same permanent magnet or the reverse magnetic pole side of the second permanent magnet. When the magnetic flux flows through the inner diameter bridge portion, the inner diameter bridge portion must be increased in order to ensure the strength, and the magnetic resistance is decreased, so that the leakage magnetic flux increases. Here, by configuring the thickness of the bridge portion to be thinner than the thickness of the portion other than the bridge portion, the magnetic resistance increases and the leakage magnetic flux can be reduced.

According to the present invention, the magnetic flux leakage of the magnet can be reduced to a minimum, and the torque of the electric motor can be further increased.

FIG. 1 is a schematic diagram of a permanent magnet embedded electric motor according to Embodiment 1 of the present invention. FIG. 2A is a top view of the rotor core of the embedded permanent magnet electric motor. 2B is a cross-sectional view taken along the line 2B-2B of FIG. 2A. FIG. 2C is a top view of the thin iron plate of the rotor core of the permanent magnet embedded motor. FIG. 3 is a configuration diagram of a rotor core of a permanent magnet embedded electric motor according to Embodiment 2 of the present invention. FIG. 4 is a configuration diagram of a rotor core of a permanent magnet embedded electric motor according to Embodiment 3 of the present invention. FIG. 5 is a configuration diagram of a rotor core of a permanent magnet embedded electric motor according to Embodiment 4 of the present invention. FIG. 6 is a configuration diagram of a rotor core of a permanent magnet embedded electric motor according to Embodiment 5 of the present invention. FIG. 7 is a configuration diagram of a rotor core of a permanent magnet embedded electric motor according to Embodiment 6 of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a permanent magnet embedded electric motor according to Embodiment 1 of the present invention, showing a cross section along a plane perpendicular to a rotation axis serving as a rotation center. The electric motor 10 includes a stator 11 and a rotor 21 disposed on the inner peripheral side of the stator 11.

The stator 11 includes a stator core 14 in which a plurality of thin steel plates are laminated in the axial direction, and a winding (not shown) wound around the stator core 14. The stator core 14 has a yoke 12, a plurality of teeth 13 formed on the inner peripheral side of the yoke 12, and a plurality of slots 15 formed between adjacent teeth 13. The winding is wound by concentrated winding or distributed winding and is accommodated in the slot 15.

The rotor 21 includes a rotor core 23 in which a plurality of first magnet embedding holes 22 and a plurality of second magnet embedding holes 25 are formed at predetermined intervals in the circumferential direction, and a first magnet embedded in the first magnet embedding hole 22. A permanent magnet 24 and a second permanent magnet 26 embedded in the second magnet embedding hole 25. The rotor core 23 is configured by laminating a plurality of thin steel plates in the axial direction. The first permanent magnet 24 and the second permanent magnet 26 are sandwiched and fixed by upper and lower end plates, or are fixed by a resin, an adhesive, or the like. A rotating shaft 20 is inserted in the center of the circular surface of the rotor 21, and the rotating shaft 20 extends from the center of the circular surface in both vertical directions. The rotating shaft 20 of the rotor 21 is rotatably supported by a bearing (not shown). The rotor 21 faces the inner peripheral surface of the teeth 13 of the stator 11 via an air gap. The direction in which the rotating shaft 20 extends is the axial direction, and the circular surface of the rotor 21 has a radial direction around the rotating shaft 20 and a radial direction from the center of the rotating shaft 20 to the outer periphery. This will be described as a direction. Further, in the radial direction of the circular surface of the rotor 21, the side having the rotation shaft 20 will be described as the inner peripheral side, and the side having the outer periphery will be described as the outer peripheral side.

In the present embodiment, as shown in FIG. 1, in the rotor 21, a plurality of first permanent magnets 24 are arranged at equal intervals in the circumferential direction. Furthermore, each 1st permanent magnet 24 is arrange | positioned so that a cross section is a rectangle and a radial direction may become a long side. The second permanent magnets 26 are arranged between the circumferential directions of the first permanent magnets 24, respectively. That is, the first permanent magnets 24 and the second permanent magnets 26 are alternately arranged in the circumferential direction. Each of the second permanent magnets 26 has a rectangular cross section and is arranged so that the circumferential direction is a long side, that is, the radial direction is a short side. Further, the respective second permanent magnets 26 are arranged on the inner peripheral side further than the inner peripheral side end portion of the first permanent magnet 24 and at equal intervals in the circumferential direction.

Also, both the first permanent magnet 24 and the second permanent magnet 26 have magnetic poles on the long side of the rectangular cross section. That is, the magnetization direction of the first permanent magnet 24 is substantially perpendicular to the q axis, and the magnetization direction of the second permanent magnet 26 is substantially parallel to the d axis. Here, the d-axis is a straight line passing through the center of the rotor 21 and the magnetic pole central portion of the magnetic pole formed on the rotor 21, and the q-axis is the magnetic pole formed on the center of the rotor 21 and the rotor 21. It is a straight line passing through between the magnetic poles.

Furthermore, the surface facing the circumferential direction of the adjacent first permanent magnet 24 and the outer peripheral surface of the second permanent magnet 26 are the same pole, and the region surrounded by these three surfaces is one magnetic pole. In the present embodiment, an example in which four magnetic poles are formed in this way is shown. In other words, as shown in FIG. 1, the q-axis extends between the adjacent second permanent magnets 26 and further through the center of the first permanent magnet 24 in the radial direction from the center of the rotor 21. ing. The d-axis extends between the first permanent magnets 24 adjacent to each other, passes through the center of the second permanent magnet 26, and extends in the radial direction from the center of the rotor 21.

In FIG. 1, the number of poles of the rotor 21 is 4 and the number of slots of the stator 11 is 6. However, the present invention is not limited to this combination, and other combinations are possible. It can also be applied. Moreover, although the 1st permanent magnet 24 and the 2nd permanent magnet 26 use a neodymium sintered magnet, a neodymium bond magnet, a ferrite sintered magnet, a ferrite bond magnet, etc., it does not specifically limit to this.

FIG. 2A is a top view showing the rotor core 23 before the first permanent magnet 24 and the second permanent magnet 26 are inserted. 2B is a 2B-2B cross-sectional view showing a cross section of 2B-2B in FIG. 2A. FIG. 2C is a top view of the thin steel plate 30 constituting the rotor core 23. As shown in FIG. 2A, the first magnet embedding hole 22 and the second magnet embedding hole 25 have shapes slightly larger than the cross-sectional areas of the first permanent magnet 24 and the second permanent magnet 26 to be inserted, respectively. Yes. Accordingly, as a matter of course, in the rotor core 23, the plurality of first magnet embedded holes 22 and the plurality of second magnet embedded holes 25 have the same arrangement relationship as the first permanent magnet 24 and the second permanent magnet 26. Is formed. That is, the plurality of first magnet embedding holes 22 are arranged at equal intervals in the circumferential direction in the rotor core 23 so that each hole shape is rectangular and the radial direction is a long side. The plurality of second magnet embedding holes 25 are respectively provided between the circumferential directions of the first magnet embedding holes 22 and further on the inner peripheral side than the inner peripheral end of the first magnet embedding hole 22. The shape is a rectangle and the radial direction is a short side. Further, the q-axis extends between the adjacent second magnet embedding holes 25 and further through the center of the first magnet embedding hole 22 in the radial direction from the center of the rotor core 23. The d-axis extends between the adjacent first magnet embedding holes 22 and further through the center of the second magnet embedding hole 25 in the radial direction from the center of the rotor core 23. The first permanent magnet 24 and the second permanent magnet 26 are respectively inserted into the first magnet embedding hole 22 and the second magnet embedding hole 25 and mechanically fixed by an end plate or the like, or an adhesive or resin Fix and fix with.

In the present embodiment, the outer periphery of the rotor core 23 will be described by taking an example of a perfect circle shape as shown in FIG. 2A. However, the distance from the center is the q-axis with the d-axis portion as the outermost diameter. It may be configured by a curve or a straight line so that the distance from the center becomes smaller as it goes.

The rotor core 23 is formed by laminating a plurality of thin steel plates 30 having a plate thickness d1, as shown in the 2B-2B sectional view of FIG. 2B. Each thin steel plate 30 is laminated in the axial direction so that the positions of the first magnet embedding hole 22 and the second magnet embedding hole 25 coincide. Thus, as a matter of course, the shape of the surface of the thin iron plate 30 is the same as the shape of the upper surface of the rotor core 23 shown in FIG. 2A, as shown in FIG. 2C. That is, also in the thin steel plate 30, the plurality of first magnet embedding holes 22 are arranged on the q-axis so that the hole shapes are rectangular and the radial direction is a long side at regular intervals in the circumferential direction. . The plurality of second magnet embedding holes 25 are respectively provided between the circumferential directions of the first magnet embedding holes 22 and further on the inner peripheral side than the inner peripheral end of the first magnet embedding hole 22. They are arranged on the d-axis so that the shape is rectangular and the radial direction is the short side.

Then, as shown in FIG. 2C, a short side 22si on the inner peripheral side of the first magnet embedding hole 22 of the thin iron plate 30 and a short side 25s of the two second magnet embedding holes 25 facing the short side 22si. A region having a substantially triangular shape surrounded is referred to as an inner diameter bridge portion 28. That is, the thin steel plate 30 has a configuration in which an iron plate outer peripheral portion 31 that forms the outer peripheral side of the thin plate iron plate 30 and an iron plate inner peripheral portion 32 that forms the inner peripheral side of the thin plate iron plate 30 are connected by a plurality of inner diameter bridge portions 28. . Further, in the thickness direction of the thin steel plate 30, the plate thickness d2 of the inner diameter bridge portion 28 is thinner than the plate thickness d1 of the thin plate iron plate 30, as shown in FIG. 2B. That is, the inner diameter bridge portion 28 is thinned by crushing the thin iron plate 30 with, for example, a press so that the plate thickness d2 is thinner than the iron plate outer peripheral portion 31 and the iron plate inner peripheral portion 32 which are other portions. Is formed. Further, in the present embodiment, as shown in FIG. 2C, a region in which the first magnet embedding hole 22 and the two second magnet embedding holes 25 are respectively connected by the boundary line 28a at the three shortest distances is provided. Such an inner diameter bridge portion 28 is used. As described above, in the present embodiment, the short side 22si on the inner peripheral side of the first magnet embedded hole 22 and the short side 25s of the two second magnet embedded holes 25 facing the short side 22si are connected to each other. A region surrounded by the three boundary lines 28 a is an inner diameter bridge portion 28.

With such a configuration, the leakage magnetic flux passes through the inner diameter bridge portion 28 in the rotor 21, but the magnetic resistance increases by reducing the plate thickness to d2, and the leakage magnetic flux is reduced. Moreover, the leakage magnetic flux from the side surface on the short side of the permanent magnet cross section to the inner bridge portion 28 can also be reduced. For this reason, leakage flux can be reduced even if the flux barrier hole conventionally provided on the side surface of the magnet embedding hole is not provided or smaller than the conventional one, and the permanent magnet can be enlarged.

In the longitudinal cross section of the thin steel plate 30, the boundary of the inner diameter bridge portion 28 is provided with a gradient 28c that smoothly changes from the plate thickness d1 to d2, as shown in a circular enlarged partial view 2BB in FIG. 2B. Yes. The gradient 28c may be configured as a curve or a straight line, or may be stepped.

The stress generated by the centrifugal force when the rotor rotates concentrates on the boundary surface that changes from the plate thickness d1 to the plate thickness d2. On the other hand, by providing the slope 28c in this portion, the stress can be dispersed as a whole without concentrating on a specific location, so that the strength of the rotor can be ensured and high-speed rotation can be achieved.

Hereinafter, as the second to sixth embodiments, examples in which the configuration of the thin steel plate 30 is partially modified from the present embodiment will be described, but the rotor core 23 and the rotor 21 are described in the present embodiment described above. It is configured in the same way.

(Embodiment 2)
In the first embodiment, the range in which the inner diameter bridge portion 28 is provided is a region in which the first magnet embedding hole 22 and the two second magnet embedding holes 25 are connected to each other by the three straight boundary lines 28a at the shortest distance. . In the second embodiment, as shown in FIG. 3, a region of the inner diameter bridge portion 28 having a plate thickness d2 thinner than the plate thickness d1 of the thin steel plate 30 is enlarged toward the inner and outer diameter sides by a boundary line 28b. That is, in the inner diameter bridge portion 28 of the present embodiment, the boundary line 28b connecting the first magnet embedding hole 22 and the two second magnet embedding holes 25 to each other is outside the boundary line 28a of the first embodiment. The shape is a bulging area. More specifically, the two boundary lines 28b between the first magnet embedding hole 22 and the second magnet embedding hole 25 swell in the direction of the iron plate outer peripheral portion 31, and one boundary between the second magnet embedding holes 25 is formed. The boundary line 28 b swells in the direction of the iron plate inner peripheral portion 32.

As mentioned above, in this Embodiment, the external shape between the embedding holes of the internal diameter bridge part 28 is expanded outside so that the area | region of the internal diameter bridge part 28 may become large. Thus, by projecting a part of the inner diameter bridge portion 28, which is a region having a small plate thickness, and increasing the area of the inner diameter bridge portion 28, the magnetic resistance of the flow path of the leakage magnetic flux can be increased. It is possible to further reduce the leakage magnetic flux.

(Embodiment 3)
FIG. 4 is a top view of the thin iron plate 30 according to the third embodiment. As shown in FIG. 4, in the present embodiment, the outer diameter bridge portion 29 is a region surrounded by the outer periphery of the thin steel plate 30 constituting the rotor core 23 and the short side 22so on the outer peripheral side of the first magnet embedding hole 22. It is said. The plate thickness d3 of the outer diameter bridge portion 29 is configured to be smaller than the plate thickness d1 of the thin steel plate 30. There are magnetic fluxes generated from the first permanent magnet 24 that pass through the inner diameter bridge portion 28 and those that pass through the outer diameter bridge portion 29. In FIG. 1, the leakage flux of the inner diameter bridge portion 28 is reduced. In addition to this, by reducing the plate thickness of the outer diameter bridge portion 29, the leakage flux can be further reduced. A torque motor can be realized.

Here, the plate thickness d3 of the outer diameter bridge portion 29 may be the same as or different from the plate thickness d2 of the inner diameter bridge portion 28. Further, instead of providing the outer diameter bridge portion 29, a region corresponding to the outer diameter bridge portion 29 may be cut out from the thin steel plate 30.

(Embodiment 4)
FIG. 5 is a top view of the thin steel plate 30 according to the fourth embodiment. As shown in FIG. 5, in the present embodiment, the short side 22si on the inner peripheral side of the first magnet buried hole 22 and the short side 25s of the second magnet buried hole 25 facing the short side 22si are in contact with each other. An elongated hole portion 27 that penetrates the inner diameter bridge portion 28 is provided. That is, the hole portion 27 is provided on the outer periphery of the inner diameter bridge portion 28.

In the first to third embodiments, the leakage magnetic flux from the side surface on the short side of the permanent magnet cross section to the inner diameter bridge portion 28 can be reduced by reducing the plate thickness. By further providing the hole 27, the leakage magnetic flux can be further reduced, and a high torque motor can be realized. As the outer shape of the inner diameter bridge portion 28, the shape shown in the first and third embodiments can be applied.

(Embodiment 5)
FIG. 6 is a top view of the thin iron plate 30 according to the fifth embodiment. As shown in FIG. 6, in the present embodiment, an inner diameter bridge portion 28 is provided in a region surrounded by the first magnet embedding hole 22 and the two second magnet embedding holes 25 as in the first to third embodiments. Yes. Further, in the present embodiment, a hole portion 40 penetrating the inner diameter bridge portion 28 is provided in the vicinity of the center on the inner side of the inner diameter bridge portion 28. In order to minimize the volume of the iron core of the inner diameter bridge portion 28 through which the leakage magnetic flux passes, the leakage magnetic flux can be reduced and a high torque motor can be realized by providing the hole portion 40 having an arbitrary shape. As the outer shape of the inner diameter bridge portion 28, the shape shown in the first and third embodiments can be applied.

(Embodiment 6)
FIG. 7 is a top view of the thin steel plate 30 according to the seventh embodiment. As shown in FIG. 7, in the present embodiment, since the cross-sectional shape of the second permanent magnet 26 is changed from a rectangular shape to a shape having a curved surface, the shape of the second magnet embedding hole 25 is also curved on the outer peripheral side accordingly. It has a shape that has By making the side surface of the second permanent magnet 26 a curved surface, the generated magnetic flux can be increased, and the leakage magnetic flux can be reduced by reducing the thickness of the portion on the side surface of the permanent magnet where the leakage magnetic flux is likely to be generated. it can. It is particularly useful for bonded magnets with a high degree of freedom in shape.

Note that the cross-sectional shape of the second permanent magnet 26 in FIG. 7 is a kamaboko shape in which one of the two long sides is a straight line and the other one is a curve. However, the shape is not limited to this and is U-shaped or V-shaped. It may be the shape.

The application field of the present invention is not particularly limited, and can be widely used as, for example, an electric motor including a permanent magnet embedded rotor.

DESCRIPTION OF SYMBOLS 11 Stator 12 Yoke 13 Teeth 14 Stator iron core 15 Slot 20 Rotating shaft 21 Rotor 22 1st magnet embedding hole 23 Rotor iron core 24 1st permanent magnet 25 2nd magnet embedding hole 26 2nd

permanent magnet

27, 40 Air | hole Part 28 inner diameter bridge part 29 outer diameter bridge part 30 thin steel plate 30

Claims

A stator in which a winding is wound around a stator core; and a rotor provided rotatably via an inner peripheral surface of the stator and a gap;
The rotor is
a rotor core having a first magnet embedding hole provided on the q axis and a second magnet embedding hole provided on the d axis;
A first permanent magnet inserted into the first magnet embedding hole;
A second permanent magnet inserted into the second magnet embedding hole,
The rotor core is configured by laminating a plurality of thin steel plates,
In the thin steel plate, a plate of an inner diameter bridge portion which is a region surrounded by a short side on the inner peripheral side of the first magnet embedding hole and two short sides of the second magnet embedding hole facing the short side. A permanent magnet embedded type electric motor characterized in that the thickness is smaller than the thickness of the thin steel plate.
The embedded permanent magnet electric motor according to claim 1, wherein an outer shape between the embedded holes of the inner diameter bridge portion is expanded outward.
The plate thickness of the outer diameter bridge portion, which is a region surrounded by the outer periphery of the rotor core and the short side of the outer periphery of the first magnet embedding hole, is smaller than the plate thickness of the thin steel plate. 3. An embedded permanent magnet electric motor according to 1 or 2.
3. The embedded permanent magnet electric motor according to claim 1, wherein a region surrounded by an outer periphery of the rotor core and a short side on an outer peripheral side of the first magnet embedding hole is cut out. 4.
The embedded permanent magnet motor according to claim 1, wherein a hole portion that penetrates the inner diameter bridge portion is provided on an outer periphery of the inner diameter bridge portion.
The embedded permanent magnet motor according to claim 1, wherein a hole portion that penetrates the inner diameter bridge portion is provided inside the inner diameter bridge portion.
The embedded permanent magnet motor according to claim 1, wherein a boundary surface in the thickness direction of the bridge portion is configured by a curve or a straight line having an arbitrary gradient.
2. The embedded permanent magnet electric motor according to claim 1, wherein the magnetization direction of the first permanent magnet is perpendicular to the q-axis, and the magnetization direction of the second permanent magnet is parallel to the d-axis. .