KR20150022087A - Interior Permanent Magnet Synchronous Machine - Google Patents

Abstract

The present invention relates to an interior permanent magnet synchronous machine. In an interior permanent magnet synchronous machine which has a through hole where a shaft is installed by penetrating, and a rotor which has a plurality of barriers for installing a permanent magnet around the through hole, the barriers of the rotor has an asymmetrical structure where ribs of various shapes are formed at the ends of both sides. The rotor has a first rotor and a second rotor which are separated from each other based on a stack direction length. The barriers of the second rotor are arranged with the same column in a direction opposite to that of the barriers of the first rotor, which have asymmetrical structure and are aligned to form a same column, to face each other. Accordingly, the rotor is divided into constant regions in a stack direction. The barrier or/and the permanent magnet formed in one region and another region are asymmetric. Because there is no necessity for manufacturing a notching or skew structure like an existing invention, it can be easily manufactured, has superior assembly, reduces caulking torque and torque ripple, and maintains torque performance.

Description

[0001] Interior Permanent Magnet Synchronous Machine [0002]

[0001] The present invention relates to a permanent magnet synchronous motor, and more particularly to a permanent magnet synchronous motor in which a rotor is divided into a predetermined region in a lamination direction, and a rotor in one region and a region in the other is divided by a barrier and / Type permanent magnet synchronous motor in which torque is not reduced while reducing cogging torque and torque ripple.

In general, an Interior Permanent Magnet Synchronous Machine (IPMSM), which is mainly used as an electric motor or a traction motor of a hybrid vehicle, is driven in a torque control mode and controls a magnetic flux and a torque current A vector control that independently controls is performed.

1, a permanent magnet synchronous motor 10 includes a plurality of holes 14 (not shown) through which coils (not shown) are wound and around which bar-shaped conductors are embedded and fixed, And a rotor 13 rotatably provided with a gap between the stator 11 and the stator 11. The rotor 13 is fixed to the center by a shaft A through hole 12 is formed. Here, a plurality of barriers 16 are formed at regular intervals between the through holes 12 and the holes 14. The permanent magnets 18 are embedded in the perforations 16.

The permanent magnet 18 is embedded in the barrier 16 and installed in the barrier 16. The permanent magnet 18 is embedded in the barrier 16 and is interposed between the barrier 16 and the permanent magnet 18, .

That is, when a current is applied to the coil, the rotor 13 is rotated by the interaction between the rotating magnetic field generated due to the structure of the stator 11 and the induced current generated in the conductor, A torque due to the permanent magnet 16 and a reluctance torque due to the structure of the rotor 13 are generated and the rotor 13 is rotated to generate torque .

However, the above-mentioned permanent magnet synchronous motor 10 has a cogging torque due to the barrier 16 of the rotor 13 and the permanent magnet 18 embedded in the barrier 16 Torque ripple is generated, which makes it difficult to control the torque ripple.

Recently, a number of measures for reducing the cogging torque and torque ripple have been proposed. Among them, in order to increase the number of slots in the core of the rotor or the stator, to form the auxiliary pole or auxiliary slot, Instead of installing permanent magnets in series, a skew structure is used which makes a difference in installation angles.

However, the notching or skew structure is complicated in its structure, so that it is very difficult to manufacture and assembling is not good. In addition, the notching or skew structure requires a lot of manufacturing cost due to complicated manufacture of a large number of dies, Resulting in a problem of deterioration. In addition, when the skew structure is applied to a motor for traction, an optimum skew angle is determined and applied to a target operation region. Therefore, there is a limit in that a torque ripple reduction effect occurs only in a constant operation region.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a recessed permanent magnet synchronous motor which is easy to manufacture and has excellent assemblability and can reduce cogging torque and torque ripple, It has its purpose.

Another object of the present invention is to provide a permanent magnet synchronous motor capable of reducing torque ripple in a wider operating range when applied to a traction motor.

According to another aspect of the present invention, there is provided a recessed permanent magnet synchronous motor including a through hole through which a shaft is inserted and a rotor having a rotor in which a plurality of barriers are embedded around the through hole, Wherein the rotor of the rotor has an asymmetric structure in which the ribs on both ends are formed in different shapes and the rotor is divided into a predetermined region on the basis of the length in the stacking direction, Wherein the barriers of the first rotor are arranged so that the asymmetric barriers are arranged in the same row, and the barriers of the second rotor are reversed and opposed to the barriers of the first rotor, In the same direction.

Here, the rotor may be divided into a first rotor and a second rotor by a half of the length in the stacking direction, the rotor may be divided into an even number equal to or more than a half of the length in the stacking direction, And the second rotators can be disposed at an intersection with each other.

In addition, skew may be further formed in at least one of the first rotor and the second rotor.

Further, the present invention is characterized in that the barrier of the first rotor has an asymmetric structure in which a permanent magnet is embedded in the left region with respect to the center of the barrier, or a permanent magnet is embedded in the right region, The barrier may have an asymmetric structure by embedding permanent magnets in positions opposite to the installed permanent magnets embedded in the barrier of the first rotor with respect to the center of the barrier.

In this case, a third rib having a predetermined width may be extended toward the stator in the central region of the first rotor and the second rotor, and at least one of the first rotor and the second rotor A skew may be formed in the rotor.

In the meantime, the recessed permanent magnet synchronous motor according to the present invention includes: a through-hole through which a shaft is inserted; and a permanent magnet synchronous motor having a rotor in which a plurality of barriers are formed around the through- The rotor is partitioned into a first rotor and a second rotor by a predetermined area based on the length in the stacking direction, and the barrier of the first rotor is provided with permanent magnets embedded in the left side of the center thereof Or permanent magnets are embedded in the right side of the permanent magnet to form an asymmetric structure. The barrier of the second rotor is embedded in the barrier of the first rotor with respect to the center of the barrier, May be embedded and installed to form an asymmetric structure.

In this case, the rotor may be divided into a first rotor and a second rotor by a half of the length in the stacking direction, the rotor may be divided into an even number equal to or more than a half of the length in the stacking direction, And the second rotor may be disposed at an intersection with each other.

Here, a third rib having a predetermined width may be formed in the central region of the first rotor and the second rotor to extend toward the stator.

In addition, skew may be further formed in at least one of the first rotor and the second rotor.

As described above, according to the recessed permanent magnet synchronous motor of the present invention, the rotor is partitioned by a predetermined region in the stacking direction, and the rotor of one region and the rotor of the other region are arranged such that the barrier and / The cogging torque and the torque ripple are reduced and the torque performance is maintained as it is, as well as being easy to fabricate and to assemble, as well as being not made with a notching or skew structure as in the prior art .

In addition, when applied to a traction motor, it is possible to provide a recessed permanent magnet synchronous motor capable of obtaining a torque ripple reduction effect in a wider operating range as compared with a case of applying a skew structure.

1 is a front view showing a conventional recessed permanent magnet synchronous motor.
FIG. 2 is a perspective view illustrating a recessed permanent magnet synchronous motor according to a first embodiment of the present invention; FIG.
Fig. 3 is a cross-sectional structural view of the first rotor and the second rotor in a state in which the rotor is divided in half in Fig. 2; Fig.
4 is a partial view showing the angle of the second rib in the barrier of the rotor.
5 is a cross-sectional view of a first rotor and a second rotor in a state where the rotor is divided in half in the recessed permanent magnet synchronous motor according to the second embodiment of the present invention.
6 is a cross-sectional view of a first rotor and a second rotor in a state where the rotor is divided in half in the recessed permanent magnet synchronous motor according to the third embodiment of the present invention.
FIG. 7 is a cross-sectional view of a first rotor and a second rotor in a state where a rotor is divided in half in a recessed permanent magnet synchronous motor according to a fourth embodiment of the present invention; FIG.
8 is a cross-sectional view of a first rotor and a second rotor in a state where the rotor is divided in half in the recessed permanent magnet synchronous motor according to the fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

≪ Embodiment 1 >

FIG. 2 is a perspective view showing a recessed permanent magnet synchronous motor according to a first embodiment of the present invention, FIG. 3 is a cross-sectional view of a first rotor and a second rotor in a state in which the rotor is divided in half in FIG. .

As shown in the drawings, the recessed permanent magnet synchronous motor 100 according to the first embodiment of the present invention includes a permanent magnet synchronous motor 100, in which coils (not shown) are wound and bar conductors are wound around and fixed A stator 102 in which a plurality of holes 114 are formed and a rotor 104 rotatably provided with a gap with the stator 102 are formed.

A through hole 112 is formed in the center of the rotor 104 so that the shaft can be fixed through the hole. A plurality of holes (not shown) for inserting and fixing bar-shaped conductors along the periphery of the stator 102 And a plurality of barriers 116 are formed at regular intervals between the through holes 112 and the holes 114. The permanent magnets 115 are arranged in a straight line Direction of the vehicle.

Here, the barrier 116 is formed at regular intervals around the through hole 112, and each barrier 116 has ribs 116a and 116b bent outward at both ends thereof. The barrier 116 116 have a different shape from one rib 116a to the other rib 116b with respect to the center thereof and are asymmetric with respect to each other.

The first rotor 110 and the second rotor 120, which are located on one side and the other side, respectively, are divided in half by the length in the stacking direction in the rotor 104 having a structure in which a plurality of plates are laminated, Are formed so as to face each other in a reversed manner.

For example, as shown in Figs. 2 and 3, the first rotor 110 positioned on one side of the lamination direction of the rotor 104 has a left rib made of a first rib 116a, And the second rotors 116b positioned on the other side are formed by stacking plates consisting of the first ribs 116a and the second ribs 116b on the other side, And the like. Here, the terms first and second ribs 116a and 116b are used to denote ribs that are not identical in shape to each other so that the barrier is asymmetric, and the shape of each rib is not limited to a specific shape.

As described above, the ribs 116a and 116b formed on both ends of the barrier ribs 116 are formed in an asymmetric structure, and are divided into halves based on the length in the stacking direction, and one of the ribs has the same barrier shape (the left rib is the first rib The first rotor 110 has a first rotor 110a and a second rotor 116b. The first rotor 110a includes a first rotor 110a and a second rotor 116b. After having the second rotor 120 laminated with plates having the same barrier shape (the left rib has the second rib 116b and the right rib has the first rib 116a) The torque ripple is reduced as compared with the conventional embedded permanent magnet synchronous motor even when the permanent magnets 115 are arranged in a row in the rotor stacking direction without a skew structure. This is because the barrier 116 of the first rotor 110 has the left rib formed by the first rib 116a and the right rib formed by the second rib 116b, The left rib of the barrier 116 is formed as the second rib 116b and the right rib is formed as the first rib 116a so as to be opposite to the one rotator 110 so as to be opposed to each other, The cogging is compensated for.

4 is a partial view showing the angle of the second rib 116b in the barrier 116 of the rotor 104. The angle of the second rib 116b is applied at various angles as shown in Table 1 below, The torque ripple was measured after combining the various designs (Taguchi method), and the results are shown in Table 2 below.

Variable Angle θ1 147 ㅀ, 149 ㅀ, 151 ㅀ θ2 38 ㅀ, 41 ㅀ, 44 ㅀ θ3 17 ㅀ, 17.5 ㅀ, 18 ㅀ

Model θ1 θ2 θ3 Torque ripple (%) Model 1 147 ㅀ 38 ㅀ 17 ㅀ 5.88 Model 2 147 ㅀ 41 ㅀ 17.5 ㅀ 4.58 Model 3 147 ㅀ 44 ㅀ 18 ㅀ 5.79 Model 4 149 ㅀ 38 ㅀ 17.5 ㅀ 5.20 Model 5 149 ㅀ 41 ㅀ 18 ㅀ 6.88 Model 6 149 ㅀ 44 ㅀ 17 ㅀ 5.11 Model 7 151 ㅀ 38 ㅀ 18 ㅀ 7.60 Model 8 151 ㅀ 41 ㅀ 17 ㅀ 4.51 Model 9 151 ㅀ 44 ㅀ 17.5 ㅀ 5.62

As shown in FIG. 4,? 1 represents the angle between the upper side of the horizontal direction of the barrier 116 and the upper side of the second rib 116b,? 2 represents the angle between the lower side of the barrier 116 And reference numeral 3 denotes a reference line connecting the center of the through hole 112 of the rotor 104 to the center of the barrier 116 and a reference line connecting the center of the through hole 112 of the rotor 104 and the lower side of the second rib 116b, And the reference line connecting the center of the second rib 116b to the center of the second rib 116b.

As a result of measuring the torque ripple after designing the angles of θ1, θ2 and θ3 according to the various angles as shown in Table 2 by the Taguchi method, θ1 is 151 Ω , the torque ripple is the smallest when θ2 is 41 ㅀ and θ3 is 17..

For reference, in the case of the recessed permanent magnet synchronous motor 100 according to the first embodiment of the present invention, the rotor 104 is divided in half with respect to the plate stacking direction to form the first rotor 110 and the second rotor 110 The asymmetric structure of the barrier 116 of the first rotor 110 and the barrier asymmetric structure of the second rotor 120 are opposed to each other so as to face each other, But also to an electric motor rotated in both directions.

As described above, in the case of the recessed permanent magnet synchronous motor 100 according to the first embodiment of the present invention, only the shape of the barrier 116 is changed, and in order to reduce the cogging torque and the torque ripple, The magnetic clearance due to the notching is not increased, so that the reduction of the torque is not caused and only the cogging torque and the torque ripple are reduced.

Further, since there is no need to provide a skew for cogging torque and torque ripple reduction as in the conventional art, the cogging torque due to skew is not reduced and torque reduction is not caused. Thus, not only cogging torque and torque ripple are reduced, Since the magnets can be installed in a line in the rotor lamination direction, the assembling property can be greatly improved. In addition, when applied to a traction motor, it is not a method of determining the skew angle that is optimized for the target operation region, so that a torque ripple reduction effect can be obtained in a wider operating range than in a skew structure.

Meanwhile, in the first embodiment of the present invention, the rotor 104 is divided in half with respect to the stacking direction, and the first rotor 110 having the above-described structure is disposed in one of the regions, The second rotor 120 having the same structure as that of the first rotor 120 is disposed so as to be opposite to the other and arranged to be opposite to each other. However, the second rotor 120 may be divided into two or more The first rotor 110 and the second rotor 120 may be arranged so as to intersect with each other in sequence, and the same effect can be obtained in this case as well.

≪ Embodiment 2 >

5 is a cross-sectional view of a first rotor and a second rotor divided in half by a rotor in the recessed permanent magnet synchronous motor according to the second embodiment of the present invention.

The second embodiment of the present invention differs from the first embodiment in that it has an asymmetric structure because permanent magnets are selectively embedded in the left region or the right region of the barrier 116-1.

That is, both the ribs of the barrier 116-1 are formed in the same shape, and the permanent magnets 115-1 are embedded or installed in the left area with respect to the center of the barrier 116-1, The permanent magnets 115-1 are embedded in the right region with respect to the center of the permanent magnets 115-1, thereby having an asymmetric structure.

Also in the second embodiment of the present invention, the rotor 104-1 is divided into a first rotor 110-1 and a second rotor 120-1 based on the length in the stacking direction, The permanent magnet 115-1 is embedded in the left side region of the barrier 116-1 and the second rotor 120-1 is provided with the permanent magnet 115-1 in the right side region of the barrier 116-1 The first rotor 110-1 and the second rotor 120-1 are inverted and opposed to each other because the permanent magnets 115-1 are embedded and installed.

Of course, permanent magnets are embedded in and installed in the right area of the barrier 116-1 of the first rotor 110-1, and permanent magnets are embedded in the left area of the barrier 116-1 of the second rotor 120-1. And may be installed and installed.

As described above, the rotor 104-1 is divided into a first rotor 110-1 and a second rotor 120-1 by the length in the stacking direction, and one rotor is provided with a barrier 116 -1, permanent magnets 115-1 are embedded in the left region of the barrier 116-1, and the permanent magnets 115-1 are embedded in the right region of the barrier 116-1 in the other rotor, When the first and second rotators are inverted and opposed to each other while embracing the permanent magnet, the same or extremely similar operation effect as in the first embodiment will be obtained. .

For reference, in the drawing, reference numeral 112-1 denotes a through hole through which a shaft is embedded.

On the other hand, in the second embodiment of the present invention, the rotor 104-1 is divided into at least two equal parts (four equal parts, six equal parts) based on the lamination direction, The second rotors 120 may be disposed so as to be sequentially crossed. In this case, the same effect can be obtained.

≪ Third Embodiment >

6 is a cross-sectional view of a first rotor and a second rotor in a state where the rotor is divided in half in the recessed permanent magnet synchronous motor according to the third embodiment of the present invention.

The third embodiment of the present invention is a modification of the second embodiment described above, and the same parts as those of the second embodiment will be denoted by the same reference numerals, and repeated description thereof will be omitted.

As shown in the drawing, the recessed permanent magnet synchronous motor according to the third embodiment of the present invention includes a third rib 116c having a predetermined width toward the stator in the central region of the barrier 116-1 of the rotor 104-1, As shown in FIG.

That is, in the state where the permanent magnets 115-1 are embedded in one of the left and right regions of the barrier 116-1, the region where the permanent magnets 115-1 are embedded and installed, And the third rib 116c is extended toward the stator in a central region that defines the third rib 116c.

When the third rib 116c is extended in the central region of the barrier 116-1 as described above, the effect of concentrating the magnetic flux in the region in which the permanent magnet 115-1 is embedded and installed is increased and the asymmetry is further strengthened The reduction of the torque is not generated, and the cogging torque and the torque ripple are further reduced. Here, the central region of the barrier does not always mean the exact center of the barrier, the region where the permanent magnets are installed, and the region where the permanent magnets are not provided, and the magnetic flux concentrating effect is smaller than the case where the third ribs 116c are not formed There is no particular limitation on the position in which it can be placed.

<Fourth Embodiment>

FIG. 7 is a cross-sectional view of a first rotor and a second rotor in a state where the rotor is divided in half in the recessed permanent magnet synchronous motor according to the fourth embodiment of the present invention. As shown in FIG. 7, The fourth embodiment of the present invention shows a configuration in which the configurations according to the first and second embodiments are mixed.

That is, the rotor 104-2 is divided into a first rotor 110-2 and a second rotor 120-2 based on the length of the lamination direction, and one of the rotors is divided into a first rotor 110-2 and a second rotor 120-2, The shape of both ribs 116a and 116b is formed in a different shape as in the first embodiment and the permanent magnets 115-1 are embedded in any one of the areas of the barrier 116 as in the second embodiment Respectively. The other one of the rotors is formed so that the shape of both ribs 116a and 116b of the barrier 116 is different from that of any one of the rotors so that the barriers are reversed and opposed to each other, A permanent magnet is embedded and installed in a direction different from the barrier of the former.

 As described above, the first rotor 110-2 and the second rotor 120-2 are reversed to be disposed opposite to each other, so that the barrier 116 and the permanent magnets 115-1 are asymmetric with respect to each other It is possible to obtain the same or extremely similar action effect as in the first embodiment described above, so that the description of the operating relationship therebetween will be omitted.

Reference numerals 112-2 in the drawings denote through holes through which the shaft is embedded.

On the other hand, in the fourth embodiment of the present invention, in some cases, the first rotor 110-2 and the second rotor 110-2 are divided into two equal parts or more (four equal parts, six equal parts) (120-2) may be arranged so as to intersect with each other in sequence, and in this case, the same operation and effect can be obtained.

<Fifth Embodiment>

8 is a cross-sectional view of a first rotor and a second rotor in a state where the rotor is divided in half in the recessed permanent magnet synchronous motor according to the fifth embodiment of the present invention.

The fifth embodiment of the present invention is a modified example of the fourth embodiment, and the same parts as those of the fourth embodiment will be denoted by the same reference numerals, and repeated description thereof will be omitted.

As shown in the figure, in the recessed permanent magnet synchronous motor according to the fifth embodiment of the present invention, a third rib 116c having a constant width toward the stator is extended in the central region of the barrier 116 of the rotor 104-2 Formed structure.

That is, in the state where the permanent magnets 115-1 are embedded in one of the left and right regions of the barrier 115-1, the region where the permanent magnets 115-1 are embedded and installed and the region where the permanent magnets 115-1 are not embedded or installed And the third rib 116c is extended toward the stator in a central region that defines the third rib 116c.

When the third rib 116c is extended in the central region of the barrier 116 as described above, the effect of concentrating the magnetic flux in the region in which the permanent magnet 115-1 is embedded is increased and the asymmetry is further strengthened, The reduction of the torque is not generated, and the cogging torque and the torque ripple are further reduced. Here, as in the third embodiment, the central region of the barrier does not always mean the exact center of the barrier, the region where the permanent magnets are provided, and the region where the permanent magnets are not installed. In the case where the third ribs 116c are not formed The position where the magnetic flux concentration effect can be obtained is not particularly limited.

As described above, according to the recessed permanent magnet synchronous motor according to the first to fifth embodiments of the present invention, asymmetry of the magnetic flux occurs due to the structure in which the barrier and / or the permanent magnet are reversed and opposed to each other in accordance with the rotor stacking direction The torque ripple can be reduced and the torque value can be maintained at the same time without forming a notching or a skew as in the prior art. In addition, when applied to a traction motor, a torque ripple reduction effect can be obtained in a wider operating range as compared with a skew structure.

In the above description, the permanent magnets are mounted in a row in the longitudinal direction in which the rotors are stacked. However, the technical idea of the present invention is used as it is while additional skew is formed to reduce the cogging torque and torque ripple reducing effect It may increase.

The technical ideas described in the embodiments of the present invention as described above may be independently performed, or may be implemented in combination with each other. While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. It is possible. Accordingly, the technical scope of the present invention should be determined by the appended claims.

100: Recessed permanent magnet synchronous motor 102: Stator
104, 104-1, 104-2: rotors 110, 110-1, 110-2:
120,120-1,120-2: Second electron 112,112-1,112-2: Through hole
114: Hole 115, 115-1: Permanent magnet
116, 116-1: barrier 116a: first rib
116b: second rib 116c: third rib

Claims (11)

There is provided a recessed permanent magnet synchronous motor having a through hole through which a shaft is inserted and a rotor in which a plurality of barriers are formed around which a permanent magnet is embedded and installed,
The barriers of the rotor have ribs on both ends of different shapes and are formed in an asymmetrical structure with each other,
The rotor is divided into a first rotor and a second rotor by dividing the rotor into a predetermined region based on the length in the stacking direction,
The barriers of the first rotor are arranged so that the bars forming the asymmetric structure are arranged in the same row, and the barriers of the second rotor are reversed from the barriers of the first rotor to be arranged in the same direction Type permanent magnet synchronous motor.
The method according to claim 1,
Wherein the rotor is divided into a first rotor and a second rotor in half by a length in the stacking direction.
The method according to claim 1,
Wherein the rotor is divided into an even number equal to or more than two equal parts based on the length in the stacking direction, and the first rotor and the second rotor are disposed at intersections with each other.
4. The method according to any one of claims 1 to 3,
Wherein a skew is formed in at least one of the first rotor and the second rotor. &Lt; RTI ID = 0.0 &gt; 18. &lt; / RTI &gt;
4. The method according to any one of claims 1 to 3,
A permanent magnet is embedded in the left region of the barrier of the first rotor with respect to the center of the barrier, or a permanent magnet is embedded in the right region of the barrier,
Wherein the barrier of the second rotor has an asymmetric structure in which a permanent magnet is embedded in and installed in a position opposite to a permanent magnet embedded in the barrier of the first rotor with respect to the center of the barrier, Permanent magnet synchronous motor.

6. The method of claim 5,
And a third rib having a predetermined width is extended toward the stator in the central region of the barriers of the first rotor and the second rotor.
There is provided a recessed permanent magnet synchronous motor having a through hole through which a shaft is inserted and a rotor in which a plurality of barriers are formed around which a permanent magnet is embedded and installed,
The rotor is divided into a first rotor and a second rotor by dividing the rotor into a predetermined region based on the length in the stacking direction,
The barrier of the first rotor may include a permanent magnet on the left side or a permanent magnet on the right side based on the center thereof to form an asymmetric structure,
Wherein the barrier of the second rotor has an asymmetric structure in which a permanent magnet is embedded in and installed in a position opposite to a permanent magnet embedded in the barrier of the first rotor with respect to the center of the barrier, Permanent magnet synchronous motor.
8. The method of claim 7,
Wherein the rotor is divided into a first rotor and a second rotor in half by a length in the stacking direction.
8. The method of claim 7,
Wherein the rotor is divided into an even number equal to or more than two equal parts based on the length in the stacking direction, and the first rotor and the second rotor are disposed at intersections with each other.
10. The method according to any one of claims 7 to 9,
And a third rib having a predetermined width is extended toward the stator in the central region of the barriers of the first rotor and the second rotor.
10. The method according to any one of claims 7 to 9,
Wherein a skew is formed in at least one of the first rotor and the second rotor. &Lt; RTI ID = 0.0 &gt; 18. &lt; / RTI &gt;

Images