JP2002272030A - Rotor and rotating electric machine with embedded permanent magnet - Google Patents

Abstract

(57) [Summary] [Problem] A plurality of permanent magnets are embedded in a rotor core,
To provide a rotor of a rotating electric machine in which a permanent magnet constituting each pole is divided by a divided piece of a rotor core and in which a magnetic flux of the permanent magnet hardly leaks. A rotor in which a plurality of permanent magnets are buried in a rotor core of a permanent magnet type rotating electric machine, and a permanent magnet constituting each pole is divided by a divided piece of the rotor core. In step 2, the distance between the outer periphery of the permanent magnet 4 and the outer periphery of the rotor core gradually increases as the distance from the circumferential center of each permanent magnet 4 embedded in the rotor core 6 to the split piece 6c increases. The magnet 4 is formed. Permanent magnets are hardly demagnetized because of the embedded magnet type, and even if the permanent magnets that make up each pole are divided by a plurality of split pieces, the outer circumference of the rotor core is thin, so the outer circumference of the core is saturated and permanent It is possible to suppress the leakage of the magnetic flux of the magnet and prevent the output of the rotating electric machine from decreasing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor of a rotating electric machine having a permanent magnet embedded in a rotor core, and more particularly to a permanent magnet type rotating electric machine of an embedded magnet type capable of rotating at a very high speed.

[0002]

2. Description of the Related Art At the time of high-speed rotation, a large centrifugal force acts on a permanent magnet. Therefore, in a permanent-magnet-type rotating electric machine for high-speed rotation, a method of holding the permanent magnet is important. Generally, a surface magnet type rotor is used for a permanent magnet type rotating electric machine for high speed rotation. The structure of the surface magnet type rotor will be described with reference to FIG.

In the surface magnet type rotor 2, a cylindrical permanent magnet 4 is provided on the outer periphery of a rotor core 6, and the high strength non-magnetic ring 8 holds the permanent magnet 4. However, the non-magnetic ring 8
In order to hold the permanent magnet 4, the magnetic gap length is increased and the magnetic resistance is increased, so that the demagnetizing field in the permanent magnet is increased and the magnetic field is easily demagnetized at high temperatures.

On the other hand, the embedded magnet type rotor has a short magnetic gap length because a permanent magnet is embedded in the rotor core.
Permanent magnets are hard to demagnetize, but are not suitable for high-speed rotation.
The reason will be described with reference to FIG. For example, in the case of a two-pole machine, the embedded magnet type rotor 2 has a permanent magnet 4
A hole for inserting the permanent magnet 4 is provided in the rotor core 6 so that the permanent magnet 4 is not scattered, and two permanent magnets 4 are embedded in the hole. Therefore, high-speed rotation cannot be performed because stress is concentrated on the two divided pieces 6c connecting the inner peripheral portion 6a and the outer peripheral portion 6b of the rotor core 6.

Therefore, in order to solve these problems, as described in Japanese Patent Application Laid-Open No. 11-113196,
The rotor structure is an embedded magnet type, and the permanent magnets that make up each pole are divided along the circumferential direction of the rotor, increasing the number of divided pieces, dispersing stress, and enabling high-speed rotation. A method has been proposed.

[0006]

The above prior art (Japanese Patent Laid-Open No.
In JP-A No. 1-113196, in order to enable high-speed rotation, a permanent magnet constituting each pole is divided into divided pieces, and the outer peripheral portion of the rotor core and the permanent magnet are supported by a large number of divided pieces.

For this reason, the number of divided pieces (the number of divided permanent magnets) should be increased as the rotation speed is increased. It no longer links with the armature winding of the child,
The output of the rotating electric machine decreases.

An object of the present invention is to provide a rotor having a permanent magnet embedded therein which is effective in preventing demagnetization at a high temperature and a decrease in output at a high speed rotation.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a rotor in which a plurality of permanent magnets are embedded in a rotor core, and the permanent magnets constituting each pole are divided into divided pieces of the rotor core. Permanent magnets are formed so that the distance between the outer peripheral side of the permanent magnet and the outer periphery of the rotor core gradually increases from the center in the circumferential direction of each of the permanent magnets embedded in the rotor core toward one end of the divided part.

When the rotor is configured as described above, the permanent magnet is embedded in the rotor core, so that it is difficult to demagnetize. Even if the permanent magnet forming each pole is divided into a plurality of divided pieces, Since the rotor core outer peripheral portion is thinned and easily saturated, the magnetic flux of the permanent magnet is hardly leaked, and the output can be prevented from lowering.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. Fig. 1 shows an embedded magnet type permanent magnet type rotating electric machine showing one embodiment of the present invention, Fig. 2 shows the conventional structure of an embedded magnet type permanent magnet type rotating electric machine, and Fig. 3 shows the results of magnetic field analysis of the terminal voltage waveform at no load. Show.

Although the figure shows a two-pole machine in which the number of permanent magnets per pole is four, the number of poles is not limited and the number of permanent magnets per pole is divided into a plurality. It just needs to be done.

As described above, in the case of a surface magnet type rotor,
Since there is a problem that the permanent magnet tends to be demagnetized at high temperatures, an embedded magnet type may be used in consideration of this point. However, in the case of an embedded magnet type rotor, the outer periphery of the rotor core
Since the permanent magnet 6b and the permanent magnet 4 are held by the divided pieces 6c connecting the inner peripheral part 6a and the outer peripheral part 6b of the rotor core, the number of the divided pieces 6c must be increased in accordance with the rotation speed.

When the number of divided pieces 6c is increased (the number of divided permanent magnets 4 constituting each pole is increased), in the case of an embedded magnet type rotor, the circumference of the permanent magnet 4 (the outer peripheral portion 6b of the rotor core, Since the peripheral part 6a and the split piece 6c) are iron cores, the permanent magnet 4
Magnetic flux wraps around the split piece 6c and does not link with the armature winding of the stator 1.

Therefore, the embedded magnet type rotor has a structure in which the magnetic flux of the permanent magnet hardly leaks, that is, a structure in which the rotor core 6 around the permanent magnet 4 is saturated to reduce the magnetic flux leakage (rotation around the permanent magnet 4). It is necessary to make the core 6 thinner).

As shown in FIG. 2, the permanent magnet cross section of the conventional embedded magnet type rotor has a rotor outer circumference and a permanent magnet outer circumference concentric, and a radial distance from the permanent magnet outer circumference to the rotor outer circumference. Becomes constant. As described above, in the case of the embedded magnet type rotor, since the stress concentrates on the split piece 6c, the permanent magnet
The place where 4 is buried is determined in consideration of the mechanical strength near the divided piece 6c.

Therefore, when the radial distance from the outer periphery of the permanent magnet to the outer periphery of the rotor is constant as in the conventional structure,
There is a margin in the mechanical strength at the center in the circumferential direction of the permanent magnet 4, and the permanent magnet 4
It has been found that the thickness H2 of the outer periphery of the rotor core at the center in the circumferential direction of No. 4 may be thin.

That is, in the embedded magnet type rotor 2 for high speed rotation, as shown in FIG. 1, the outer peripheral side of the permanent magnet 4 and the rotor The permanent magnet 4 may be formed such that the distance from the outer periphery of the iron core gradually increases. With such a shape, the rotor core outer peripheral portion 6b is thinned and easily saturated, so that the magnetic flux of the permanent magnet 4 does not easily leak.

When the permanent magnet 4 is divided by the divided pieces 6c, the surface area of the permanent magnet 4 is reduced by the amount of the divided pieces 6c, and the magnetic flux generated from the permanent magnet 4 is reduced. If the permanent magnets 4 are formed such that the distance between the outer peripheral side of the permanent magnets 4 and the outer periphery of the rotor core gradually increases as approaching the divided piece 6c from the circumferential center of each permanent magnet 4, the outer periphery of the rotor and the permanent magnets Since the surface area of the permanent magnet 4 can be increased as compared with the case where the outer periphery is concentric, a decrease in the magnetic flux of the permanent magnet can be suppressed.

FIG. 3 shows the results of a magnetic field analysis of the no-load terminal voltage waveform. The conventional structure shown in the figure is a case where the radial distance from the outer periphery of the permanent magnet to the outer periphery of the rotor is constant (FIG. 2). In the case where the distance between the outer peripheral side of the permanent magnet 4 and the outer periphery of the rotor core is gradually increased as approaching (the thickness of the outer periphery 6b of the rotor core is changed so that H2 / H1 = 1/2 in FIG. 1). When it is). The voltage value in the figure is
The relative value is displayed with the maximum value of the induced voltage of the conventional structure as a reference (1.0).

From this result, in this case, the terminal voltage is increased by about 10%, and the distance between the outer peripheral side of the permanent magnet 4 and the outer periphery of the rotor core from the center in the circumferential direction of each permanent magnet 4 toward the divided piece 6c is increased. Is gradually increased, the magnetic flux linked to the armature winding increases, and the terminal voltage of the armature winding can be increased.

Therefore, even if the permanent magnet 4 constituting each pole is divided by the plurality of divided pieces 6c, it is possible to prevent the output from decreasing without reducing the magnetic flux linked to the armature winding.

[0023]

As described above, according to the present invention, the permanent magnet is hardly demagnetized, and the magnetic flux of the permanent magnet is hardly leaked even if the permanent magnet of each pole is divided by a plurality of divided pieces. Thus, it is possible to prevent the output of the rotating electric machine from decreasing.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a rotating electric machine showing one embodiment of the present invention.

FIG. 2 is a sectional structural view of a conventional rotating electric machine.

FIG. 3 is a no-load induced voltage waveform according to the present invention.

FIG. 4 is a conventional sectional structural view of a rotating electric machine according to the present invention.

FIG. 5 is a conventional sectional structural view of a rotating electric machine according to the present invention.

[Explanation of symbols]

1 ... stator, 2 ... rotor, 3 ... stator slot, 4 ... permanent magnet, 5 ... shaft, 6 ... rotor core, 6a ... inner circumference of rotor core, 6b ... outer circumference of rotor core, 6c ... Divided piece, 7 ... stator core, 8 ... retaining ring.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Kikuchi 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Mika Takahashi 7, Omikamachi, Hitachi City, Ibaraki Prefecture No. 1-1 F-term in Hitachi Research Laboratory, Hitachi Ltd. (Reference) 5H002 AA02 AB07 AC06 AE08 5H621 AA03 GA01 GA12 GA15 HH01 HH09 JK05 5H622 AA04 CA02 CA07 CA14 CB04 CB05 PP11

Claims (5)

[Claims] In a rotor in which a plurality of permanent magnets are embedded in a rotor core and the permanent magnets constituting each pole are divided by a split piece, each permanent magnet embedded in the rotor core is separated. A rotating electric machine wherein the permanent magnet is formed such that the distance between the outer peripheral side of the permanent magnet and the outer periphery of the rotor core gradually increases as the circumferential thickness of the magnet approaches the split piece from the center. Rotor. 2. A rotor in which a plurality of permanent magnets are buried in a rotor core and the permanent magnets constituting each pole are divided into divided pieces. An insertion hole for the permanent magnet is provided so that a radial thickness gradually increases from the center in the circumferential direction of the permanent magnet toward the divided piece, and the permanent magnet is embedded in the insertion hole. Rotor of rotating electric machine. 3. A plurality of permanent magnets are embedded in a rotor core, the permanent magnets constituting each pole are divided by a segment of the rotor core, and the thickness of the permanent magnet in the radial direction is reduced. A rotating electric machine comprising a rotor that becomes smaller toward its end and has a convex shape in the outer peripheral direction. 4. A rotating electric machine comprising a rotor in which a plurality of permanent magnets are embedded in a rotor core, and wherein the permanent magnets constituting each pole are divided by a divided piece of the rotor core. Permanent magnets were formed so that the distance between the outer peripheral side of the permanent magnet and the outer periphery of the rotor core gradually increased as approaching the divided piece from the circumferential center of each permanent magnet embedded in the rotor core. A rotating electric machine comprising a rotor. 5. A rotating electric machine comprising a rotor in which a plurality of permanent magnets are embedded in a rotor core, and wherein the permanent magnets constituting each pole are divided by a segment of the rotor core. An insertion hole for the permanent magnet is provided such that a radial thickness of a rotor core at an outer peripheral portion of the permanent magnet becomes gradually thicker as approaching the divided piece from a circumferential center portion of the permanent magnet. A rotating electric machine comprising a rotor having a permanent magnet embedded therein.