JPH08251847A - Permanent magnet type rotary machine - Google Patents

Abstract

PURPOSE: To provide a permanent magnet type rotary machine which assures a low cogging torque, while keeping the skew effect by changing the arrangement of the permanent magnets. CONSTITUTION: In a permanent magnet type rotary machine comprising a ring type stator 1 having a plurality of salient poles 11 projected toward inside and a rotor 2 provided opposed to the internal side of the salient poles 11 via a gap and arranging a plurality of permanent magnets 3 in the circumferential direction, the salient poles 11 and permanent magnets 3 are divided into four blocks 1' to 4' in the circumferential direction with equal intervals and the positional relationships of the salient poles 11 and permanent magnets 3 of one pair of blocks 1', 3' and the other pair of blocks 2', 4' provided symmetrically for the center of the rotor among the blocks are arranged in the similar shape geometrically. The permanent magnet 3 of the other pair of blocks 2', 4' is deviated in the circumferential direction for fixing so that the cogging torque generated in one pair of blocks 1', 3' is canceled by the cogging torque of the other pair of blocks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet type rotary electric machine in which a rotor is provided with a permanent magnet.

[0002]

2. Description of the Related Art Conventionally, in a permanent magnet type rotating electric machine, for example, when the rotor of the permanent magnet has 8 poles and the stator has 12 slots, as shown in FIG. 5, it projects inside the ring-shaped stator 1. A salient pole 11 is provided, a rotor 2 facing the salient pole 11 via a gap is provided, and a plurality of rectangular permanent magnets 3 having a quadrangular periphery are arranged at equal intervals in the circumferential direction on the outer circumference of the rotor 2. is there. When the permanent magnets 3 are arranged in parallel to the axial direction, when the permanent magnets 3 are divided into four blocks, that is, the blocks are geometrically congruent as shown in FIG.
The permanent magnets 3 and the salient poles 11 in each block have exactly the same positional relationship. Since the magnetic flux distribution periodically changes at the boundaries of the blocks, the cogging torques of these four blocks are exactly equal in magnitude and phase. Therefore, the total cogging torque is four times as large as the cogging torque of each block, and the cogging torque is extremely large, which causes a problem that smooth rotation cannot be performed. As a method for solving this problem, the permanent magnet is formed into a so-called skewed shape having an inclination with respect to the axial direction, or, for example, as shown in FIG. It is disclosed that a plurality of permanent magnets 3B are arranged in the axial direction as well as a plurality of permanent magnets 3B in the circumferential direction, and the permanent magnets 3B are slightly shifted in the circumferential direction as they advance in the axial direction to provide a skew effect. For example, Shokai 6
1-17876, Jitsukaihei 3-86752).

[0003]

However, the prior art permanent magnet having a skewed shape has a problem that when the permanent magnet is formed by sintering or casting, the permanent magnet is largely deformed and the number of processing steps is large. It was Further, in the case where the permanent magnets are arranged so as to be displaced in the axial direction, since the magnetic poles having different polarities are close to each other in the axial direction, a magnetic flux flows between the adjacent magnetic poles. For example, since the S pole 3A _S of the permanent magnet 3A and the N pole 3B _N of the permanent magnet 3B shown in FIG. 7 are close to each other, the S pole 3A _S and the N pole 3 do not flow to the stator.
There is a problem in that a leakage magnetic flux as indicated by an arrow is generated between B _N and B _N, and as shown in FIG. 8, the magnetic flux distribution in the circumferential direction of the rotor does not become a sine wave, and the skew effect on the cogging torque becomes small. there were. SUMMARY OF THE INVENTION It is an object of the present invention to provide a permanent magnet type rotating electric machine having a low cogging torque by changing the arrangement of permanent magnets to maintain the skew effect.

[0004]

In order to solve the above problems, the present invention is directed to a ring-shaped stator provided with a plurality of salient poles protruding inwardly, and facing the inside of the salient poles with a gap. In a permanent magnet type rotating electric machine provided with a rotor having a plurality of permanent magnets arranged in the circumferential direction, the convex pole and the permanent magnet are divided into four blocks at equal intervals in the circumferential direction,
The positional relationship between the convex pole and the permanent magnet in one pair of blocks and the other pair of blocks which are symmetrical with respect to the center of the rotor among the blocks is geometrically determined. With a congruent arrangement, the permanent magnets of the other pair of blocks are displaced in the circumferential direction so that the cogging torque generated in the one pair of blocks cancels each other out. It is fixed. In addition, it is provided with 12 convex poles and 8 permanent magnets, and the positions of the permanent magnets of the other pair of blocks are set in the circumferential direction with respect to the positions of the permanent magnets of the one pair of blocks. In addition, the cogging torque generated in one of the pair of blocks is fixed at a position rotated by 1/2 the mechanical angle of one cycle. In addition, a ring-shaped stator having a plurality of salient poles protruding inward, and a plurality of permanent magnets facing the inner side of the salient poles of the stator via a gap and skewed in the circumferential direction and the axial direction. In a permanent magnet type rotating electric machine including a rotor in which magnets are arranged, a gap between permanent magnets adjacent in the axial direction is made larger than a gap between permanent magnets adjacent in the circumferential direction. is there.

[0005]

By the above means, the cogging torque generated from one pair of blocks located symmetrically with respect to the center of the rotor and the cogging torque generated from the other pair of blocks are deviated from each other by a half cycle. They cancel each other out and the overall cogging torque is greatly reduced. Further, since the south pole of one permanent magnet and the north pole of the permanent magnet axially adjacent to each other are separated by a gap larger than the gap of the magnets circumferentially adjacent to each other, the south pole and the north pole adjacent to each other in the axial direction. There is no leakage magnetic flux between and, and the magnetic flux distribution in the circumferential direction of the rotor becomes a sine wave, and the cogging torque is reduced.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a first embodiment of the present invention.
A permanent magnet type rotary electric machine having 12 poles will be described as an example. In the figure, reference numeral 1 denotes a ring-shaped stator, which is provided with twelve salient poles 11 which are arranged at equal intervals in the circumferential direction and project inward, and twelve slots 12 are provided between adjacent salient poles 11. And a stator coil is housed in the slot 12. 2 is a rotor, 21 is a rotor core formed by laminating thin steel plates, and eight permanent magnets 3 each having a quadrangular periphery are fixed to the outer periphery of the rotor core 21.
A method of arranging the permanent magnets 3 on the rotor 2 will be described. When the stator 1 and the rotor 2 are divided into four blocks by being divided into four in the circumferential direction, a position symmetrical to the center of the rotor 2 is provided. A pair of blocks and a block of permanent magnets 3
Are geometrically congruent, and the outer circumference of the rotor 2 is arranged at angular intervals divided by the number of magnetic poles. The other pair of blocks and the permanent magnets 3 of the blocks, which are symmetrically positioned with respect to the center of the rotor 2, are geometrically congruent,
7.5 clockwise for blocks and blocks
It is fixed at the position where it is rotated once. For the positioning of the permanent magnet 3, when the rotor core 21 is punched out, a protrusion is provided on the outer circumference of the rotor core 21 in accordance with the position of the permanent magnet in each block, and the permanent magnet 3 is arranged in accordance with the protrusion.
The permanent magnet can be easily positioned without increasing the number of processing steps.

The principle of generation of cogging torque will be described. In the conventional example described with reference to FIG. 5, the permanent magnets 3 are arranged on the outer circumference of the rotor 2 at equal intervals, and as shown in FIG.
Since the cogging torque generated in 1 has the same phase and magnitude, the total cogging torque is four times the cogging torque of each block. Further, one cycle of the cogging torque is a mechanical angle, and an angle (15 degrees) obtained by dividing 360 degrees by the least common multiple (24) of the number of magnetic poles (8) and the number of slots (12).
become. Therefore, in order to achieve balance, the two geometrically congruent blocks and the permanent magnet 3 of the block, which are symmetrical with respect to the center of rotation of the rotor 2, are left as they are. Similarly, the positions of the block and the permanent magnet 3 of the block, which are symmetrical with respect to the rotation center of the rotor 2, are 1/2 cycle of the cogging torque in mechanical angle.
The block and the permanent magnet 3 of the block are rotated clockwise by ½ of 7.5 degrees so that the block and the block have different positional relationships and are geometrically congruent. As a result, the cogging torque generated from the block and the cogging torque generated from the block are offset from each other by a half cycle as shown in FIG. 2, and therefore cancel each other out, and the overall cogging torque is greatly reduced.

FIG. 3 is a side view showing a second embodiment of the present invention, showing a rotor in which two rows of eight-pole permanent magnets are arranged in the axial direction. In the figure, 2 is a rotor, 21 is a rotor core,
3A is a permanent magnet in which eight rotor magnets are arranged on the outer circumference of the rotor core 21 at equal intervals. 3B has the same number of permanent magnets 3A as the outer circumference of the rotor core 21 at equal intervals, and a gap G ₂ wider than the gap G ₁ between the permanent magnets 3A in the axial direction in the circumferential direction is opened. 15 which is 1/2 cycle of cogging torque
Arranged by shifting in the circumferential direction by 7.5 degrees, which is 1/2 the degree,
It is designed to have a skew effect. Therefore,
S pole 3A _S of permanent magnet 3A and N pole 3B _{N of} permanent magnet 3B
Is separated by a gap G ₂ which is larger than the gap G ₁ between the magnets adjacent to each other in the circumferential direction, so that no leakage magnetic flux is generated between the S pole 3A _S and the N pole 3B _N , as shown in FIG. Thus, the magnetic flux distribution in the circumferential direction of the rotor becomes a sine wave, and the cogging torque is reduced.

[0009]

As described above, according to the present invention, the circumferential positional relationship between the stator and the rotor is divided into a plurality of circumferentially magnetically identical blocks, and each block is divided into blocks. Since the fixed position of the permanent magnet is moved so as to cancel the cogging torque, the same effect as that obtained by skewing the permanent magnet can be obtained even if the permanent magnet has a rectangular periphery. Also,
When arranging multiple permanent magnets in the axial direction and displacing them in the circumferential direction, make the gap between the magnets in the axial direction larger than the gap between the magnets in the circumferential direction to reduce the leakage flux and cogging. Since the generation of torque is suppressed, there is an effect that it is possible to provide a permanent magnet type rotary electric machine that has an extremely low cogging torque and a low man-hour and cost for manufacturing a permanent magnet.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing cogging torque according to the first embodiment of this invention.

3 (a) is a front view and FIG. 3 (b) is a side view showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing cogging torque according to a second embodiment of the present invention.

FIG. 5 is a front view showing a conventional example.

FIG. 6 is an explanatory diagram showing a cogging torque of a conventional example.

7A is a front view and FIG. 7B is a side view showing a conventional example.

FIG. 8 is an explanatory diagram showing a cogging torque of a conventional example.

[Explanation of symbols]

1 stator, 11 convex poles, 12 slots, 2 rotors, 21 rotor cores, 3A, 3B permanent magnets, G
₁ , G ₂ gap

Claims (3)

[Claims] 1. A rotor having a ring-shaped stator provided with a plurality of salient poles protruding inward, and a plurality of permanent magnets disposed inside the salient pole, facing each other with a gap and circumferentially arranged. In the permanent magnet type rotating electric machine including the above, the convex pole and the permanent magnet are divided into four blocks at equal intervals in the circumferential direction,
The positional relationship between the convex pole and the permanent magnet in one pair of blocks and the other pair of blocks which are symmetrical with respect to the center of the rotor among the blocks is geometrically determined. With a congruent arrangement, the permanent magnets of the other pair of blocks are displaced in the circumferential direction so that the cogging torque generated in the one pair of blocks cancels each other out. Permanent magnet type rotating electrical machine characterized by being fixed. 2. The convex pole having 12 poles and the permanent magnet having 8 poles are provided, and the positions of the permanent magnets of the other pair of blocks are set to the positions of the permanent magnets of the one pair of blocks. The permanent magnet type rotating electric machine according to claim 1, wherein the permanent magnet type rotating electric machine is fixed at a position rotated by 1/2 an angle of a mechanical angle of one cycle of cogging torque generated in the one pair of blocks in the circumferential direction. 3. A ring-shaped stator provided with a plurality of salient poles protruding inward, and facing the inner side of the salient poles of the stator through a gap and skewed in the circumferential and axial directions. In a permanent magnet type rotating electric machine including a rotor in which a plurality of permanent magnets are arranged, a gap between permanent magnets adjacent in the axial direction is larger than a gap between permanent magnets adjacent in the circumferential direction. A permanent magnet type rotary electric machine characterized by the above.