JPH05137304A - Synchronous motor capable of reducing cogging torque - Google Patents

Abstract

PURPOSE:To make the magnitude of cogging torque reducible without changing the number of magnetic poles and that of slots in a synchronous motor having the structure of the slots multiplied by a natural number. CONSTITUTION:The rotor 16 of the title synchronous motor is equipped with a plurality of permanent magnets 12 radially arranged around an output shaft 10 and with a plurality of yokes 14 circumferentially arranged between these permanent magnets 12 and respectively forming magnetic poles. Each yoke 14 has a predetermined arc-shaped outer peripheral face 22 facing a stator 20 via air-gap part. The stator 20 is equipped with slots 18 being the natural number of times as many as the magnetic poles. The rotor 16 is equipped with two sorts of permanent magnets 12a, 12b differing in thickness and arranged one by one alternately in the circumferential direction. Respective vertexes 24 of the outer peripheral faces 22 of the yokes 14 are arranged in the manner of alternately approaching and separating by 1/4 of the slot pitch angle of the stator 20 in the mutually approaching and separating directions from a standard arrangement, where the vertexes are at equal spaces circumferentially of the rotor 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous motor, and in particular, it is unavoidable from the disturbance of the magnetic flux due to the slots that are essentially formed for winding installation on the stator circumferential surface facing the rotor of the synchronous motor. In order to reduce the generated cogging torque as much as possible, in particular, a rotor having rotor yokes and permanent magnets arranged alternately in the circumferential direction and a slot number that is a natural number (n) times the number of magnetic poles of this rotor are provided. The present invention relates to an improved structure of a synchronous motor that can reduce the magnitude of the cogging torque without changing the number of magnetic poles and the number of slots in the synchronous motor including the stator.

[0002]

2. Description of the Related Art When a synchronous motor rotates, torque pulsation, or so-called cogging torque, is usually generated in proportion to the number of teeth of the stator core, that is, the number of slots essentially provided in the stator core for installing windings. To do. This cogging torque has a slot opening on the circumferential surface of the stator facing the rotor, so that the magnetic path of the field magnetic flux generated from the magnetic pole of the rotor when the rotor and the stator move relative to each other is This is due to the fact that the magnetic pole periodically changes every time it crosses the magnetic pole, and the magnetic flux distribution in the air gap between the rotor and the stator is disturbed.

Therefore, the cycle and magnitude (variation width) of this cogging torque depend on the number of slots provided in the stator core. It is well known that the smaller the generation cycle of the cogging torque, the smaller the size of the cogging torque. Therefore, it is considered that the cogging torque can be reduced by increasing the number of slots. However, the number of slots of the stator core is inevitably determined by the number of magnetic poles of the rotor, the number of phases of the electric motor, the winding form, etc. Also, increasing the number of slots indiscriminately complicates the stator structure. Bring

For example, in a three-phase AC driven synchronous motor, at least three windings are required to form a single-layer winding on the stator of an M-pole motor having M rotor permanent magnets.
M slots, or a natural number multiple of 3 nM slots are required. When the stator core is provided with 3M slots, each phase (U phase, V
Phase, W phase) three slots containing the windings face each other,
The winding is configured to make one turn for two poles (that is, one pole pair of N pole and S pole). At this time, the polarities of the currents flowing in the windings of one coil are opposite in polarity to the adjacent N poles and S poles of the rotor 1 pole pair, so that the torques applied to these 1 pole pairs are in the same direction. , Which is taken out as the output of the electric motor. The same applies to the cogging torque generated by the existence of the slot opening.

FIG. 7 shows an example of an electric motor having this type of natural number times slot structure. The synchronous motor shown in FIG.
Six permanent magnets 2 are arranged radially around the output shaft 1, and a yoke 4 or a yoke 3 arranged between the permanent magnets 2 surrounds the rotor 4, which constitutes six magnetic poles. A stator 6 having 36 slots 5. Therefore, in this electric motor, six slots 5 face one pole of the rotor 4. A winding (not shown) is housed in each slot 5. The outer peripheral surface 3a of the yoke 3 of the rotor 4 has a predetermined arc shape such that the magnetic flux density generated from the rotor 4 exhibits a substantially sinusoidal waveform, assuming that the inner peripheral surface 6a of the stator 6 has no opening by the slot 5. It is formed in a shape. Therefore, this arc shape is bilaterally symmetrical with respect to the apex 7 of the outer peripheral surface 3a, and the apexes 7 are arranged at equal intervals (center angle 60 °) between the yokes 3.

In such a structure, the rotor 4 is actually
The magnetic flux generated from the sine wave is disturbed in the sine waveform due to the opening 8 of the slot 5, and this causes the cogging torque. The magnetic flux distribution at this time is conceptually shown in FIG. Figure 8
Is predicted when, for example, the magnetic pole, that is, the outer peripheral surface of the yoke 3 is scanned to measure the magnetic flux distribution when the rotor 4 is stationary, and the waveform recess 9 that causes cogging torque is characteristically shown. .. As can be seen from the figure, while one magnetic pole of the rotor 4, that is, one yoke 3 is rotated by 12 slots (electrical angle 360 °, mechanical angle 120 °), twelve corrugated concave portions 9 are regularly (electrical angle). 1 for every 30 °
Occurs). In this electric motor, since the corrugated recess 9 is generated in the same direction in synchronization with the N pole and the S pole of the rotor 1 pole pair, the size thereof is twice that of one corrugated recess 9 and the cogging torque of the whole is reduced. The fluctuation range is extremely large. In this case, the synchronism of the cogging torque cannot be eliminated by simply increasing the number of slots to 3 nM.

Therefore, the number of slots facing one pole of the rotor is made non-natural by making the winding form of the stator multi-layered so that the generation of cogging torque is regulated between the N pole and the S pole in one pole pair of the rotor. There has already been provided an electric motor capable of offsetting each other and canceling each other to reduce the fluctuation range of the cogging torque of the entire rotor. In such an electric motor having a non-natural multiple slot structure, the N and S poles in one pole pair of the rotor are not synchronized with each other in the generation of the corrugated concave portions and are regularly displaced. Therefore, the number of times the corrugated recesses are generated is twice the number of slots per one rotation of the rotor, and the size of each corrugated recess is reduced as compared with the above-described natural multiple times slot structure. Since the output torque of the rotor cancels out, the fluctuation range of the cogging torque of the entire rotor decreases.

[0008]

In the electric motor having the non-natural number times slot structure described above, the number of slots facing one magnetic pole of the rotor is made non-natural so that the magnitude of the cogging torque is reduced as described above. Can be reduced as However, the number of slots formed in the stator is inevitably limited by the number of poles of the rotor, etc. as described above, and the natural number times slot structure as described above must be adopted due to these various restrictions. No effective measures have yet been provided for electric motors.

The present invention has been eagerly and devised to solve such problems, and the object thereof is that the number of slots of the stator is a natural number per one magnetic pole of the rotor. It is an object of the present invention to provide a synchronous motor capable of reducing the magnitude of cogging torque by an extremely easy means without changing the number of magnetic poles and the number of slots.

[0010]

In order to achieve the above object, the present invention provides a plurality of permanent magnets radially arranged around an output shaft and circumferentially arranged between these permanent magnets. A rotor having a plurality of yokes each having a magnetic pole formed on each of them, and having a circumferential surface that bulges into a predetermined arc shape and faces the stator through a gap, and a rotor facing the yoke circumferential surface of the rotor, In a synchronous motor including a stator having slots for winding installation, the number of which is a natural multiple of the number of magnetic poles, in the rotor, the apex of the plurality of yoke peripheral surfaces having the predetermined arc shape is With respect to the standard arrangement arranged at equal intervals in the circumferential direction of the rotor, the arrangement relationship is such that the quarter of the pitch angle of the slot of the stator is approaching and separating from each other and alternately approaching and separating. Comprising a yoke positioning means for arranging a plurality of yokes, to provide a synchronous motor, characterized in that it has a structure to distribute the magnetic flux of the disturbance in the rotating direction of the gap portion due to the slot.

According to a preferred embodiment of the present invention, there is provided a synchronous motor in which the yoke positioning means comprises two types of the permanent magnets having different thicknesses, which are alternately arranged one by one in the circumferential direction of the rotor. To be done. Further, the yoke positioning means may be composed of the permanent magnets of the same size, which are alternately arranged in different numbers in the circumferential direction of the rotor. Further, it is also convenient to construct the yoke positioning means one by one in the circumferential direction of the rotor by the permanent magnets of the same size, which are alternately arranged close to each other on the outer peripheral side and the inner peripheral side of the rotor.

Further, the rotor is composed of two rotor blocks divided in the axial direction, and in each rotor block, the yoke positioning means has the plurality of yokes, and each of the vertices of the peripheral surface thereof has the above-mentioned. The two blocks are arranged so as to have an arrangement relationship in which they approach and separate from each other by a quarter of the pitch angle of the slots from the standard arrangement and alternately approach and separate, and the two blocks are arranged so as to have a pitch of the slots. It is also possible to adopt a configuration in which they are connected to each other while being rotated by ¼ of the angle.

[0013]

With the yoke positioning means, the apexes of the plurality of peripheral surfaces of the yoke are moved from the standard arrangement equidistant in the circumferential direction of the rotor toward and away from each other by ¼ of the pitch angle of the slots of the stator. Further, when the yokes are arranged so as to approach and separate alternately, with respect to a pair of adjacent yokes,
With respect to the intervals of the vertices, a group that is closer to each other by ½ of the pitch angle of the slot and a group that is apart from the equally spaced position in the circumferential direction are alternately arranged. As a result, when the rotor rotates, the corrugated concave portions generated in the sinusoidal waveform of the magnetic flux in the air gap between the rotor and the stator due to the slots of the stator have a pitch angle of the slot in one adjacent pair of yokes, that is, one pole pair of the rotor. It is generated by being shifted by 1/2. Therefore, the number of occurrences of the corrugated recesses per one rotation of the rotor is twice the number of slots, the size of the corrugated recesses per rotation is reduced, and the torque due to the corrugated recesses and the original output torque cancel each other. The fluctuation range of the cogging torque of the rotor as a whole is reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail based on its embodiments with reference to the accompanying drawings. In all the drawings, the same constituents will be referred to with the same signs. Figure 1
1 shows a sectional view of a synchronous motor according to a first embodiment of the present invention. This synchronous motor has a structure with 6 poles and 36 slots, that is, a natural number times slot structure in which a natural number (six) status lots face one rotor pole. Therefore, this synchronous motor has six permanent magnets 1 around the output shaft 10.
2, the rotors 16 are arranged radially, and the yokes 14 disposed between the permanent magnets 12 form six magnetic poles, and the stator 20 having the 36 slots 18 surrounding the rotor 16.

Like the rotor in the conventional synchronous motor (see FIG. 7), the rotor 16 has a predetermined arc in which the outer peripheral surface 22 of the yoke 14 facing the stator 20 expands symmetrically about its apex 24. The outer surface 2 of the yoke 14 is drawn when the rotor 16 rotates.
The magnetic flux density generated from the rotor 16 exhibits a substantially sinusoidal waveform due to the periodic change in the air gap between the rotor 2 and the inner peripheral surface 20a of the stator 20. At this time, the magnetic flux density actually generated from the rotor 16 is disturbed in the sinusoidal waveform (waveform concave portion) due to the opening 18a of the slot 18, which causes cogging torque.

The permanent magnets 12 arranged between the yokes 14 of the rotor 16 have different thicknesses between two adjacent permanent magnets 12, and a thin permanent magnet 12a and a thick permanent magnet 12b.
And are arranged alternately in the circumferential direction. These permanent magnets 12a and 12b form the yoke positioning means of the present invention, and the positions of the vertices 24 of the outer peripheral surface 22 of each yoke 14 are arranged at equal intervals in the conventional circumferential direction due to the difference in thickness. It has changed from the standard layout to a layout in which the intervals change regularly. That is, between adjacent yokes sandwiching the thin permanent magnet 12a, 1/2 of the pitch angle (mechanical angle 10 °, electrical angle 30 °) of the slots 18 of the stator 20 (mechanical angle 5).
Angle, electrical angle 15 °), so that the adjacent yokes sandwiching the thick permanent magnet 12b are separated from each other by ½ of the pitch angle of the slots 18,
The yokes 14 are regularly arranged. Therefore,
The thickness of the thick permanent magnet 12b is approximately twice that of the thin permanent magnet 12a.

Each yoke 14 of the rotor 16 is generally formed of a laminated body of electromagnetic steel plates, and a through hole 28 for a tie rod 26 for integrally fixing the yoke 14 is provided at a substantially central position of each yoke 14. In the embodiment shown in FIG. 1, these tie rods 26 are equally spaced in the circumferential direction, that is, the central angle is 60 °.
It is arranged for each. Therefore, as clearly shown in FIG. 2, the angle between the straight line α connecting the rotation center O of the rotor 16 and the center point C of the through hole 28 and the straight line β connecting the rotation center O and the apex 24 of the yoke 14 is: In each yoke 14.
It becomes 5 °. At this time, as described above, each vertex 24
The deflection directions of are alternately opposite.

The operation of the synchronous motor having the rotor 16 having the above structure will be described below. In the above synchronous motor, when the rotor 16 is rotated, the magnetic flux distribution is generated between the outer peripheral surface 22 of the yoke 14 and the inner peripheral surface 20a of the stator 20 on a sine waveform of one yoke 14 for 12 times per cycle. Corrugated recesses are generated (that is, once for every 30 electrical degrees). In the conventional motor having a natural number times slot structure, the corrugated concave portions are simultaneously generated in the adjacent one-pole pair yokes as described above, and the fluctuation range of the cogging torque is increased. However, in the electric motor of FIG. 1, the positions of the vertices 24 of the outer peripheral surfaces 22 of the two adjacent yokes 14 forming one pole pair of the rotor 16 are closer to or farther from each other by a mechanical angle of 5 °. Between the fourteen, the generation timings of the corrugated concave portions generated on the respective sine waveforms are deviated from each other by an electrical angle of 15 ° (mechanical angle of 5 °).
Therefore, in this electric motor, in two adjacent yokes 14, that is, in one pole pair of the rotor 16, the corrugated recesses, which are doubled 24 times per cycle, are generated once every 15 ° electrical angle. In this way, the generation of corrugated recesses, which were locally concentrated in the conventional electric motor, is dispersed at multiple points, and the torque due to the corrugated recess and the original output torque cancel each other out, so that the cogging torque The fluctuation range is reduced.

From another point of view of the configuration of FIG. 1, the adjacent yokes 14 are arranged so as to be offset from each other by ½ of the pitch angle of the slots 18 of the stator 20 so as to face the one pole pair of yokes 14. The number of slots 18 to be set is 11.
The number is reduced to 5, and a non-natural number of slots 18 are forcibly opposed to one pole. Therefore, it can be said that the above-described effects are almost the same as the effects produced by the electric motor having the conventional non-natural multiple slot structure.

In the above-described embodiment, the tie rods 26 for integrally fixing the yoke 14 of the rotor 16 are arranged at equal intervals in the circumferential direction of the rotor 16 from the viewpoint of dynamic balance during rotation, and therefore are shown in FIG. As described above, the installation positions of the through holes 28 for the tie rods 26 of the adjacent yokes 14 are displaced line-symmetrically on the same cross section. Therefore, by arranging two adjacent yokes 14 so that they are opposite to each other, the respective yokes 14 can be formed in the same shape. This eliminates the need to use two types of yokes and reduces the manufacturing cost.

Alternatively, by arranging the tie rods 26 in the circumferential direction of the rotor 16 at unequal intervals,
Each yoke 14 can be formed in the same shape. A modified example of the rotor 16 configured in this way is shown in FIG. As shown, the rotor 16 'has a through hole 28' for the tie rod 26, the center point C of which is the rotor 16 '.
Of the straight line β connecting the rotation center O of the
The yokes 14 'are arranged so as to be located on the upper side, so that the yokes 14' are formed in exactly the same shape without being turned upside down. At this time, the tie rods 26 are regularly arranged on the same circumference with respect to the center of rotation of the rotor 16 ', that is, alternately arranged at positions of central angles 55 ° and 65 °. Therefore, the vector sum due to the centrifugal force at the time of rotation is still 0, and the problem concerning the dynamic balance of the rotor 16 'which is a rotating member does not occur.

FIG. 4 shows a synchronous motor according to a second embodiment of the present invention in cross section with the stator omitted. The rotor 30 of this synchronous motor has substantially the same structure as the rotor 16 shown in FIGS. 1 and 2, and has six yokes 14.
The apex 24 of the outer peripheral surface 22 of the rotor is arranged in the same manner as the rotor 16 so that the yokes 14 of one pole pair adjacent to each other have an electrical angle of 15 °.
Six magnetic poles that generate magnetic fluxes whose phases are shifted by (mechanical angle 5 °) are formed. Here, in order to obtain a phase shift, in the rotor 30, the permanent magnets 32 of the same size are alternately arranged in the circumferential direction in different numbers.
That is, the thin permanent magnet 1 in the rotor 16 of FIG.
One permanent magnet 32 is placed instead of 2a, and two permanent magnets 32 are placed instead of the thick permanent magnet 12b. This makes it possible to reduce the manufacturing cost by using only one type of permanent magnet. This second
It goes without saying that the tie rods 26 can be unequally arranged in the embodiment as in the rotor 16 'shown in FIG.

FIG. 5 shows a sectional view of a synchronous motor according to a third embodiment of the invention, with the stator likewise omitted. The rotor 34 of this synchronous motor utilizes the arc shape of the outer peripheral surface 22 of the yoke 14 forming the magnetic poles to obtain the same phase shift as in the embodiment of FIGS. The arc shape of the outer peripheral surface 22 of the yoke 14 has a small radius of curvature at the edge portion (connection portion with the permanent magnet) 22a as illustrated. Therefore, if the permanent magnet is arranged closer to the outer peripheral surface 22 of the yoke 14, the edge portion 22
Since it is necessary to smoothly connect a and the permanent magnet, the interval between the adjacent yokes 14 is inevitably narrowed. So rotor 3
In No. 4, the permanent magnets 36 of the same shape are alternately arranged in the circumferential direction, one by one in proximity to the inner peripheral side and the outer peripheral side. Then, at this time, the thickness of the permanent magnet 36 may be set so that the same phase shift as in the first and second embodiments can be obtained by the above arrangement. As a result, the number of permanent magnets used is the same as the number of poles, and the manufacturing cost can be further reduced. Of course, also in this third embodiment, the tie rods 26 can be arranged unequally.

FIG. 6 is a sectional view showing a synchronous motor according to a fourth embodiment of the present invention, similarly omitting the stator. Figure 1
By using the rotors according to the respective embodiments of FIG. 5, the number of times of the waveform concave portions generated in one cycle of the magnetic flux waveform in the adjacent yokes of one pole pair is divided from 12 times synchronized in each yoke. It has increased to 24 times. Therefore, in the fourth embodiment of FIG. 6, the divided corrugated recesses of 24 times are further divided into a large number to further reduce the fluctuation range of the cogging torque as a whole. Therefore, the rotor 38 used in this embodiment, as shown in FIG.
It has a configuration in which it is divided into two blocks in the front and rear in the axial direction of the electric motor.

In the front block 40 and the rear block 42 of the rotor 38, as in the rotors according to the respective embodiments of FIGS. 1 to 5, the yokes 44 of adjacent one pole pairs mutually have an electrical angle of 15 ° (mechanical angle). Six magnetic poles that generate magnetic fluxes that are out of phase by 5 ° are formed. In the embodiment of FIG. 6, each block of the rotor 38 uses two types of permanent magnets 12 having different thicknesses as in the rotor 16 of FIG. At the same time, the phase difference of the magnetic flux between the front block 40 and the rear block 42 is set to 1/2 of the angle corresponding to the generation period of the corrugated recess left in each block (or 1/4 of the slot pitch angle of the stator), that is, the present embodiment. In the example, the electrical angle is 7.5 °
Set to (mechanical angle 2.5 °).

As shown in FIGS. 6B and 6C, in each of the front block 40 and the rear block 42,
The two adjacent yokes 44a and 44b are composed of two types of yokes in which the arrangement of the through holes 28 for the tie rods 26 is different. In this embodiment, as in the embodiment of FIG. 1, the tie rods 26 are arranged at equal intervals in the circumferential direction, and therefore the straight line α connecting the rotation center O of the rotor 38 and the center point C of the through hole 28 and the rotation The angle formed by the straight line β connecting the center O and the apex 24 of each of the yokes 44a and 44b is 1.25 ° in the yoke 44a and 3.75 ° in the yoke 44b. Then, at this time, as in the embodiment of FIG.
The deflection directions of 4 are alternately opposite.

In the front block 40 and the rear block 42 having such a structure, the yokes 44a and the yokes 44b in the respective blocks 40 and 42 are connected, and the mutual phase difference between these yokes, that is, the deflection angle of the apex 24 is determined. They are axially connected to each other so that the difference is 2.5 °. Due to the phase difference between the front and rear blocks, the front block 40
The corrugated recesses formed 24 times in each of the rear block 42 and the rear block 42 are further divided into 48 times, which further reduces the fluctuation range of the cogging torque as a whole.

The deflection angles of the apexes 24 of the two types of yokes 44a and 44b of the rotor 38 in the fourth embodiment are inevitably set from the combination of the sum of 5 ° and the difference of 2.5 °. .. More generally, the sum is 1/2 of the pitch angle of the slots 18 of the stator 20 and the difference is 1/2 of the angle corresponding to the generation period of the corrugated recess left in each block (or 1 of the slot pitch angle of the stator). It may be set from the combination of / 4).

[0029]

As described above, according to the present invention, the vertices of the predetermined arc shape on the circumferential surfaces of the plurality of yokes have a pitch angle of 1 of the slot of the stator from the equidistant positions in the circumferential direction of the rotor.
/ 4, the yoke positioning means for arranging the plurality of yokes is provided so as to approach and separate from each other and alternately approach and separate, and the arrangement rule of the yoke peripheral surface by the yoke positioning means is provided. Due to the static deflection, due to the slots in the stator during rotation of the rotor,
Since the corrugated concave portion generated in the sinusoidal waveform of the magnetic flux in the gap between the rotor and the stator is generated by being displaced by 1/2 of the pitch angle of the slots in one pair of adjacent yokes, that is, one pole pair of the rotor, The number of occurrences of the corrugated recesses per rotation is twice the number of slots, the size of the corrugated recesses per rotation is reduced, and the torque due to the corrugated recesses cancels the original output torque, resulting in cogging of the entire rotor. The fluctuation range of torque is reduced. Therefore, even in the synchronous motor having the natural number times slot structure, the magnitude of the cogging torque can be reduced by an extremely easy means without changing the number of slots of the stator and the number of magnetic poles of the rotor. The operating accuracy of can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a synchronous motor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a rotor of the synchronous motor of FIG.

3 is a cross-sectional view of a modified example of the rotor of the synchronous motor of FIG.

FIG. 4 is a sectional view of a rotor of a synchronous motor according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a rotor of a synchronous motor according to a third embodiment of the present invention.

FIG. 6 is a view of a rotor of a synchronous motor according to a fourth embodiment of the present invention, (a) side view, (b) BB sectional view, (c) C.
-C sectional drawing.

FIG. 7 is a cross-sectional view of a conventional synchronous motor.

FIG. 8 is a diagram showing a magnetic flux distribution in a gap between a stator and a rotor of a conventional synchronous motor.

[Explanation of symbols]

 10 ... Output shaft 12, 32, 36 ... Permanent magnet 14, 44 ... Yoke 16, 30, 34, 38 ... Rotor 18 ... Slot 20 ... Stator 22 ... Outer peripheral surface 24 ... Apex 26 ... Tie rod 28 ... Through hole 40 ... Front block 42 ... Rear block

Claims (5)

[Claims] 1. A plurality of devices arranged radially around an output shaft.
Of the permanent magnets and the circumferential arrangement between these permanent magnets.
To form a magnetic pole in each of the
Has a peripheral surface that bulges into a predetermined arc shape facing the rotor
A rotor having a plurality of yokes, and the rotor of the rotor.
The number of magnetic poles is a natural number times the number of the magnetic poles.
With a stator with slots for winding windings
In the term electric motor, the rotor includes the plurality of rotors having the predetermined arc shape.
The vertices of the yoke circumferential surface are arranged at equal intervals in the circumferential direction of the rotor.
With respect to the standard arrangement provided,
Only 1 / 4th of the angle in the approaching direction and separating direction,
So that they have an arrangement relationship of alternately approaching and separating from each other.
A yoke positioning means for arranging a plurality of yokes is provided,
Disturbance of magnetic flux in the void due to the slot
Is configured to be dispersed in the rotation direction.
Term electric motor. 2. The synchronous motor according to claim 1, wherein the yoke positioning means comprises two types of the permanent magnets having different thicknesses, which are alternately arranged one by one in the circumferential direction of the rotor. 3. The synchronous motor according to claim 1, wherein the yoke positioning means is composed of the permanent magnets having the same size and arranged in different numbers in the circumferential direction of the rotor. 4. The yoke positioning means comprises the permanent magnets of the same size, which are arranged one by one in the circumferential direction of the rotor and are alternately arranged close to each other on the outer peripheral side and the inner peripheral side of the rotor. Synchronous motor. 5. The rotor is composed of two rotor blocks divided in the axial direction, and in each of the blocks, the yoke positioning means has the plurality of yokes, and each of the apexes of the peripheral surface thereof is the standard. The two blocks are arranged so as to have an arrangement relationship in which they approach and separate from each other by ¼ of the pitch angle of the slot, and alternately approach and separate.
The synchronous motor according to any one of claims 1 to 4, wherein the synchronous motors are connected in a state of being mutually rotated by 1/4 of a pitch angle of the slots.