WO2010110150A1

WO2010110150A1 - Permanent magnet-embedded motor

Info

Publication number: WO2010110150A1
Application number: PCT/JP2010/054583
Authority: WO
Inventors: 浩忠長野
Original assignee: 三相電機株式会社
Priority date: 2009-03-25
Filing date: 2010-03-17
Publication date: 2010-09-30
Also published as: JP2012114970A

Abstract

A permanent magnet-embedded motor which has improved performance despite the fact that the number of permanent magnets is the same as the number of magnetic poles. A permanent magnet-embedded motor comprising; a rotor core (7) having permanent magnet containing holes (8) formed along a rotating shaft (9); and a rotor (6) provided with permanent magnets (10) inserted in the permanent magnet containing holes (8) in such a manner that, in a plane perpendicular to the rotating shaft (9), the longitudinal end surfaces of permanent magnets (10) located adjacent to each other in the circumferential direction of the rotor (6) have the same polarity. The number of the magnetic poles and the number of the permanent magnet containing holes (8) are the same, and in a plane perpendicular to the rotating shaft (9), the longitudinal surfaces of all the permanent magnet containing holes (8) are extended from the inner peripheral side to the outer peripheral side of the rotor (6) in such a manner that adjacent permanent magnet containing holes (8) do not interfere with each other and that those portions of the permanent magnet containing holes which are on the outer peripheral side (8a) of the rotor are tilted in the same circumferential direction relative to the radial direction. Thus, the permanent magnet containing holes (8) have a shape which can increase the amount of the permanent magnets. The permanent magnets (10) are provided in the permanent magnet containing holes (8).

Description

Permanent magnet embedded motor

The present invention relates to a rotor in a permanent magnet embedded type electric motor including a stator and a rotor that rotates in the stator, in particular, a permanent magnet embedded having a rotor in which a permanent magnet is embedded in a rotor core constituting the rotor. The present invention relates to a built-in electric motor.

A rotor of a conventional embedded permanent magnet electric motor has a plurality of magnet accommodation holes for accommodating permanent magnets in the direction of the rotation axis of a rotor core constituting the rotor, and each of the magnet accommodation holes has a permanent magnet. Has a rotor inserted. As the shape of the permanent magnet housing hole, various shapes considered for improving efficiency and suppressing vibration and noise are considered.

The shape of these permanent magnet accommodation holes is a circular arc shape in which the permanent magnet accommodation holes are convex on the rotation axis side and both ends are extended to the outer periphery on a plane perpendicular to the rotation axis of the rotor. The width between the two permanent magnet housing holes toward the inner peripheral side in the radial direction of the rotor on a surface perpendicular to the rotation axis of the rotor (for example, see Patent Document 1) On the surface that is narrow and convex toward the rotating shaft and has a substantially V-shape (see, for example, Patent Document 2), or in a plane perpendicular to the rotating shaft of the rotor, A substantially V-shaped permanent magnet housing hole which is convex toward the outer peripheral side, and between this substantially V-shaped permanent magnet housing hole and another substantially V-shaped permanent magnet housing hole adjacent in the circumferential direction. In addition, one having a shape in which one permanent magnet housing hole in the radial direction is additionally provided (see, for example, Patent Document 3). Etc. there is.

As described above, in the example of the rotor of the conventional embedded permanent magnet electric motor, the amount of the permanent magnet that works effectively is increased in order to increase the torque and improve the efficiency while maintaining the mechanical strength of the rotor. Yes.

However, the rotor of the permanent magnet embedded motor as described above does not have P permanent magnets with respect to the number P of magnetic poles. Basically, if there are P permanent magnets, a P-pole magnetic pole can be formed. Therefore, compared with a shape in which a plurality of permanent magnets are arranged in the circumferential direction of the rotor, these embedded permanent magnet electric motors The number of permanent magnets used in the rotor will increase. By the way, the cost of the permanent magnet includes not only the material cost but also the molding cost and processing cost required when forming the individual permanent magnets. In particular, a material with a low permanent magnet material cost is used. In this case, the ratio of the above cost increase becomes large. For this reason, even if the material used is a permanent magnet having the same volume, the cost increases as the number of permanent magnets increases.

Also, in the process of inserting permanent magnets into the permanent magnet accommodation holes of the rotor during product assembly, the smaller the number of permanent magnets, the shorter the assembly time and the lower the assembly cost.

As described above, in a rotor of an embedded permanent magnet electric motor, it is advantageous in terms of cost to use a small number of permanent magnets, but at the same time, there is a degree of freedom in the embedded shape when the permanent magnet is embedded in the rotor. Since it tends to decrease and the amount of permanent magnets to be used tends to decrease, the performance may not be satisfied.

JP-A-8-331783 JP 2008-17633 A JP 2008-199794 A

The present invention has been made in view of the above circumstances, and the problem to be solved by the present invention is to improve performance while making the number of permanent magnets of a rotor of an embedded permanent magnet motor the same as the number of magnetic poles. An object of the present invention is to provide a permanent magnet embedded type electric motor having a rotor.

According to the first aspect of the present invention for solving the above-described problems, in the first aspect of the present invention, a rotor core having a plurality of permanent magnet housing holes in the direction of the rotation axis of the rotor, and a surface perpendicular to the rotation axis of the rotor. The permanent magnet housing hole in FIG. 1 has a rotor in which a permanent magnet is inserted in which the longitudinal surfaces of permanent magnets adjacent in the circumferential direction are inserted with the same polarity. Further, the number of the plurality of permanent magnet housing holes is the same as the number of the plurality of magnetic poles of the rotor. In addition, the longitudinal surfaces of all the permanent magnet accommodation holes in the plane perpendicular to the rotation axis of the rotor are in a direction extending from the rotor inner circumference side to the rotor outer circumference side and in a range not interfering with the adjacent permanent magnet accommodation holes. The rotor outer peripheral side of the permanent magnet housing hole is inclined in the same circumferential direction with respect to the radial direction of the rotor, and the rotor has a rotor in which the permanent magnet is embedded in the permanent magnet housing hole. This is a permanent magnet embedded electric motor.

In the invention of claim 2, the permanent magnet accommodation hole has a flat plate shape in a plane perpendicular to the rotation axis of the rotor. 2. The permanent magnet embedded type electric motor according to claim 1, wherein the permanent magnet disposed in the permanent magnet housing hole has a flat plate shape.

According to a third aspect of the present invention, the flat plate-shaped permanent magnet receiving hole in which the flat plate-shaped permanent magnets are arranged on the plane perpendicular to the rotation axis of the rotor is long from the longitudinal end surface of the permanent magnet to at least one side of the longitudinal end surface. 3. The permanent magnet embedded type electric motor according to claim 2, which has a gap extending in the direction.

According to a fourth aspect of the present invention, the air gap extending in the longitudinal direction from the flat-plate-shaped permanent magnet accommodation hole on the plane perpendicular to the rotation axis of the rotor extends from at least one of the ends to the longitudinal surface side of the permanent magnet accommodation hole. 4. A permanent magnet embedded type electric motor according to claim 3, further comprising a slit.

In the invention according to claim 5, a part of the outer periphery of the rotor facing the teeth at the tip of the slot of the stator on the plane perpendicular to the rotation axis is the end of the permanent magnet housing hole on the outer periphery side of the rotor. 5. The permanent magnet embedded type electric motor according to claim 4, wherein the electric motor is formed in a flat shape in the vicinity of.

According to the first aspect of the present invention, the longitudinal surfaces of the permanent magnets adjacent to each other in the circumferential direction of the rotor are made of the same poles in the plane perpendicular to the rotation axis of the rotor. The number of permanent magnet housing holes for embedding a plurality of permanent magnets is the same as the number of magnetic poles of the rotor. Since it has a permanent magnet embedded with tilting in a range that does not interfere with the direction, compared to the case where the permanent magnet is simply arranged along the radial direction of the rotor or compared to the shape in which the permanent magnet is simply arranged along the circumferential direction, Since a longer permanent magnet can be embedded in the rotor core, the motor can be reduced in size as compared with a conventional motor having a surface magnet type (SPM) rotor. Compared to the rotor, the amount of permanent magnets Pressure is Hakare have improved the growth and the efficiency of the torque is achieved while suppressing the short-circuiting of the magnetic flux in the longitudinal ends simultaneously.

In the means of the invention of claim 2, the permanent magnet accommodation hole is formed in a flat plate shape on a surface perpendicular to the rotation axis direction of the rotor, and the shape of the permanent magnet disposed in the permanent magnet accommodation hole is a flat plate. Although the amount of permanent magnets that can be embedded in the rotor is reduced compared to permanent magnets with curved surface shapes such as arc plate shapes, the permanent magnets are designed to increase torque and improve efficiency. The manufacturing cost is reduced.

In the means of the invention of claim 3, the permanent magnet is eliminated from the longitudinal end surface of the permanent magnet accommodation hole in which the permanent magnet is disposed, and this portion is formed as a gap extending in the longitudinal direction, thereby forming an end surface portion of the permanent magnet accommodation hole. Since a region having a low magnetic permeability is formed, short-circuiting of magnetic flux can be limited, and the amount of permanent magnets in the portions where the permanent magnets at the end portions of the permanent magnets are not working effectively can be reduced. On the other hand, in a permanent magnet that is magnetized in a direction perpendicular to the longitudinal plane on a plane perpendicular to the rotational axis of the conventional rotor, the short-circuit of the permanent magnet's magnetic flux is the longitudinal end of the permanent magnet. In the state surrounded by a material with high magnetic permeability, the degree of short-circuiting of the magnetic flux was increased.

According to the fourth aspect of the present invention, since the slit extending from the outer peripheral side gap extending from the longitudinal direction of the permanent magnet housing hole to the outer peripheral direction of the rotor is provided on the surface perpendicular to the rotation axis of the rotor, the cogging torque increased with the torque. Torque ripple can be suppressed, and noise and vibration of the permanent magnet embedded motor can be efficiently suppressed by the slit length of the outer peripheral slit. Furthermore, since it has an inner peripheral side slit that extends in the outer peripheral direction of the rotor from one end of the inner peripheral side gap that extends in the inner peripheral direction of the rotor, a short circuit of magnetic flux in the inner peripheral portion of the rotor of the permanent magnet is further reduced. It can be effectively suppressed. Further, the increase in torque and the improvement in efficiency can be achieved by the slit length of the inner peripheral slit. However, if the slit length of the inner slit is increased, the strength of the rotor core also decreases, so the torque length and efficiency can be improved efficiently by optimizing the slit length of the inner slit. Is possible.

In the means of claim 5, in order to drive the rotor, it is used by being incorporated in a stator facing the rotor with a gap in a plane perpendicular to the rotor, but a part of the outer periphery of the rotor Is formed in a flat shape, the width of the gap between the rotor and the stator in this part is increased, the magnetic resistance is increased, and the teeth portion of the stator slot that opposes the rotor and the gap. The short circuit of the magnetic flux which generate | occur | produces via can be suppressed.

It is a figure which shows the surface at right angles to the rotating shaft of the rotor shown by removing the stator and fixed plate in this Embodiment. It is an enlarged view of a surface perpendicular to the rotation axis in the vicinity of the outer peripheral side gap in the present embodiment. It is an enlarged view of a surface perpendicular to the rotation axis in the vicinity of the inner circumferential side gap in the present embodiment. It is a graph which shows the relationship between the slit length Lc of the inner peripheral side slit in this Embodiment, and efficiency. It is a graph which shows the relationship between the slit length La of the outer periphery side slit in this Embodiment, the slit length Lb, and a cogging torque characteristic. (A) is a partial view of a plane perpendicular to the rotor rotation axis using a plate-shaped permanent magnet, (b) is a portion of a plane perpendicular to the rotor rotation axis using a circular plate-shaped permanent magnet FIG. It is a graph which shows the relationship between the shaft output and the efficiency which show the efficiency characteristic of the electric motor which consists of a permanent magnet embedded type (IPM) rotor of the present invention, and the electric motor which consists of a conventional surface magnet type (SPM) rotor. .

Embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to this embodiment.

FIG. 1 is a view showing a plane perpendicular to the rotation axis of an embedded permanent magnet rotor according to an embodiment of the present invention.

In a plane perpendicular to the rotation axis 9 of the rotor 6, the stator 1 is opposed to the rotor 6 through a gap 12 in the center direction from a substantially annular ring portion 2 that forms the outer diameter of the stator core 1 a. The extending 12 radial teeth 3 are formed in an annular shape. A slot 4 that is a space for winding a copper wire on both sides of each tooth 3 and an insulator (not shown) for securing insulation between the iron core of the stator 1 and the winding wire 5 when forming the winding wire 5 are provided. In addition, the wire 5 in which a copper wire is wound is provided in the space of the slot 4. This winding 5 is made by Y-connection, and the U-phase, V-phase, and W-phase windings are connected in series and connected at a neutral point.

The rotor 6 includes a rotor core 7, a rotating shaft 9 that fixes the rotor core 7, a permanent magnet 10 that is inserted into a permanent magnet accommodation hole 8 that exists inside the rotor core 7, and the rotor core 7. At both ends in the direction of the rotary shaft 9, there are fixed plates (not shown) that prevent the permanent magnet 10 from falling off. The fixed plates are fixed by rivets that penetrate the rotor 6 in the direction of the rotary shaft 9. Formed from different shapes.

The rotor core 7 is formed by laminating electromagnetic steel plates in the direction of the rotation shaft 9, and the rotation shaft 9 is inserted into and fixed to a rotation shaft insertion hole (not shown) formed in the center portion. 9 is supported inside the stator 1 in a rotatable state. Further, on the rotor core 7, the longitudinal surfaces of all the permanent magnet housing holes 8 are adjacent to each other in a direction extending from the inner peripheral side to the outer peripheral side of the rotor 6 on a plane perpendicular to the rotary shaft 9. A permanent magnet into which the permanent magnet 10 can be inserted in a shape in which the permanent magnet accommodation hole 8 on the rotor outer peripheral side 8a is inclined in the same circumferential direction with respect to the radial direction of the rotor 6 within a range not interfering with the permanent magnet accommodation hole 8. Eight receiving holes 8 corresponding to the number of magnetic poles are formed at equal intervals in the circumferential direction. Further, in order to prevent the permanent magnet 10 inserted into the permanent magnet housing hole 8 on the surface perpendicular to the rotating shaft 9 from dropping from the end surface in the rotating shaft direction of the rotor core 7 when the electric motor rotates, the rotor core 7 Are provided with rivet holes 7a through which rivets for fixing fixing plates (not shown) provided at both ends of the rotor core 7 in the direction of the rotating shaft 9 are passed.

The permanent magnet 10 is magnetized perpendicularly to the longitudinal surface in the radial direction on a surface perpendicular to the rotation axis 9 of the rotor 6, and the longitudinal surfaces of the adjacent permanent magnet accommodation holes 8 are N poles or S poles. It is inserted so as to be the same polarity. In this embodiment, in consideration of the cost of the final product, the flat permanent magnet 10 shown in FIG. 6A that can be manufactured at the lowest cost is used. However, if it is desired to achieve higher torque, the permanent magnet amount can be further increased by making the shape of the permanent magnet 10 not the flat plate shape but the arc plate shape shown in FIG. Thus, a high torque embedded permanent magnet electric motor can be realized. In these FIG. 6, the inner peripheral side gap 8c on the rotor inner peripheral side 8b at the end of the permanent magnet, the outer peripheral side gap 8d on the rotor outer peripheral side 8a, the inner peripheral side slit 8f, the outer peripheral side slit 8h, and the outer peripheral side 8i is abbreviate | omitted and it has shown typically in the state which extended the permanent magnet edge part.

The rotor core 7 has a large degree of short-circuiting of magnetic flux at the longitudinal end portions of the permanent magnets 10 of the permanent magnet receiving holes 8 on the surface perpendicular to the rotation axis 9 of the rotor 6. Therefore, in order to limit the short circuit of the magnetic flux, as the gap extending from both end portions of the permanent magnet 10 in the longitudinal direction, the inner circumference side gap 8c on the inner circumference side of the rotor 6 and the outer circumference side gap on the rotor outer circumference side 8a. 8d is provided. Further, in the vicinity of the outer periphery of the rotor of the permanent magnet 10, in order to suppress a short circuit of magnetic flux generated through the gap 12 between the stator 1 and the rotor 6 and the tip of the tooth 3 of the stator 1, A part of the annular portion which is the outer peripheral portion of the child 6 is cut out to form a flat portion 11 shown in FIG.

Furthermore, on the surface perpendicular to the rotation shaft 9, as shown in FIG. 3, the inner circumferential side gap 8c is extended in a range not contacting the adjacent permanent magnet accommodation hole 8. However, as the inner peripheral side gap 8c is extended in this manner, the width of the inner peripheral side bridge iron core 8e sandwiched between the adjacent permanent magnet accommodation holes 8 becomes narrower and the strength of the rotor core 7 decreases. Therefore, the rotor core 7 is formed by leaving the width of the sandwiched inner peripheral bridge core 8e so that the strength does not decrease. Further, the inner circumferential side slit 8f is formed in the rotor outer circumferential side 8a extending from a part of the inner circumferential side gap 8c, and the efficiency is improved by changing the slit length Lc of the inner circumferential side slit 8f. Can be improved. By the way, as the slit length Lc of the inner peripheral side slit 8f becomes longer, the strength of the rotor core 7 decreases, and the improvement in efficiency is saturated as shown in FIG. For this reason, the slit length Lc of the inner peripheral side slit 8f is formed to a length that becomes a saturation point of efficiency.

Further, as shown in FIG. 2, on the surface perpendicular to the rotating shaft 9, the outer peripheral side gap 8 d of the permanent magnet housing hole 8 extends to the vicinity of the outer periphery of the rotor 6 within a range not contacting the outer periphery of the rotor 6. Has been. However, the strength of the rotor core 7 decreases as the width of the outer peripheral bridge core 8g at the outer peripheral portion of the rotor 6 decreases. Therefore, the rotor core 7 is formed while leaving the width of the outer peripheral bridge core 8g at the outer peripheral portion of the rotor 6 as thin as the strength does not drop. Further, an outer peripheral side slit 8h and an outer peripheral side slit 8i extending from the outer peripheral side gap 8d to both sides in the circumferential direction of the rotor 6 are formed. By changing the slit length La of the outer slit 8h and the slit length Lb of the outer slit 8i, respectively, the cogging torque and torque ripple of the rotor 6 can be improved as shown in FIG. Therefore, the slit length La of the outer slit 8h and the slit length Lb of the outer slit 8i are optimized.

Further, as shown in FIG. 2, the flat shape portion 11 provided on the rotor outer peripheral side 8 a on the surface perpendicular to the rotation shaft 9 is formed by the center of the end surface of the outer peripheral portion of the rotor 6 of the permanent magnet 10 and the rotor. A linear shape in which a part of the annular portion of the outer circumference circle of the rotor 6 is cut out by a line obtained by translating a tangent at the intersection of the line passing through the center of the rotor 6 and the outer circumference of the rotor 6 to the inner circumference of the rotor 6 in the radial direction. Further, the tangent line translated and the outer periphery and intersection of the rotor 6 are formed in the rounded portion 13 without corners in order to increase the durability of the mold shape during mass production. .

In the above embodiment, the permanent magnet 10 shown in FIG. 1 is not divided with respect to the direction of the rotating shaft 9, and the number of magnetic poles of the rotor 6 and the number of permanent magnets 10 completely coincide with each other. It has become. However, when the dimension of the electric motor in the direction of the rotary shaft 9 is large, the size of the permanent magnet 10 in the direction of the rotary shaft 9 is also large, so that the production yield of the permanent magnet 10 may be deteriorated. Therefore, when the production yield of the permanent magnet 10 is deteriorated as described above, there is no problem even if the permanent magnet 10 is divided in the direction of the rotating shaft 9.

FIG. 7 is a shaft output showing the efficiency characteristics at a rotational speed of 1200 rpm, respectively, of an electric motor composed of an embedded permanent magnet (IPM) rotor of the present invention and an electric motor composed of a conventional surface magnet type (SPM) rotor. It is a graph which shows the relationship between efficiency. In this case, in the conventional SPM motor, the outer diameter of the stator (stator) is φ122 mm, the stator thickness is 65 mm, the length of the permanent magnet is 75 mm, and the volume of the permanent magnet is 10705 mm ³ . In the embedded permanent magnet (IPM) motor of the present invention, which has substantially the same output and efficiency as the conventional SPM motor, the outer diameter of the stator is 112 mm, the stator thickness is 55 mm, the length of the permanent magnet The thickness is 60 mm, and the volume of the permanent magnet is 8006 mm ³ . That is, in the permanent magnet embedded type electric motor of the present invention, when the performance is substantially the same as that of the conventional surface magnet type electric motor, the size of the embedded permanent magnet electric motor of the present invention is the same as that of the conventional surface magnet. The outer diameter of the stator can be reduced to 6.6%, the stator thickness can be reduced to 15.4%, the length of the permanent magnet can be 20%, and the volume of the permanent magnet can be reduced to 25%. The permanent magnet embedded type electric motor of the invention is small in size and high in performance.

DESCRIPTION OF SYMBOLS 1 Stator 1a Stator iron core 2 Annular part 3 Teeth 4 Slot 5 Winding 6 Rotor 7 Rotor iron core 7a Rivet hole 8 Permanent magnet accommodation hole 8a Rotor outer peripheral side 8b Rotor inner peripheral side 8c Inner peripheral side gap 8d Outer peripheral side Air gap 8e Inner peripheral side bridge iron core 8f Inner peripheral side slit 8g Outer peripheral side bridge iron core 8h Outer peripheral side slit 8i Outer peripheral side slit 9 Rotating shaft 10 Permanent magnet 11 Flat shape part 12 Air gap 13 Round part La Slit length Lb Slit length Lc Slit length

Claims

A rotor core having a plurality of permanent magnet accommodation holes in the direction of the rotation axis of the rotor and a longitudinal surface of a permanent magnet adjacent in the circumferential direction to the permanent magnet accommodation hole in a plane perpendicular to the rotation axis of the rotor core are made to have the same polarity. The number of the plurality of permanent magnet receiving holes is the same as the number of the plurality of magnetic poles of the rotor, and is perpendicular to the rotation axis of the rotor. The rotors of the permanent magnet accommodation holes are such that the longitudinal surfaces of all the permanent magnet accommodation holes in the same surface extend from the rotor inner circumference side to the rotor outer circumference side and do not interfere with adjacent permanent magnet accommodation holes. An embedded permanent magnet electric motor comprising a rotor in which an outer peripheral side is inclined in the same circumferential direction with respect to a radial direction and a permanent magnet is embedded in the permanent magnet housing hole.
2. The permanent magnet according to claim 1, wherein the permanent magnet accommodation hole in a plane perpendicular to the rotation axis of the rotor core has a flat plate shape, and the permanent magnet disposed in the permanent magnet accommodation hole has a flat plate shape. Embedded electric motor.
The flat-plate-shaped permanent magnet housing hole in which flat-plate-shaped permanent magnets are arranged in a plane perpendicular to the rotation axis of the rotor core has a gap extending in the longitudinal direction from the longitudinal end surface of the permanent magnet on at least one side of the longitudinal end surface. The embedded permanent magnet electric motor according to claim 2.
The air gap extending in the longitudinal direction from the flat plate-shaped permanent magnet accommodation hole in a plane perpendicular to the rotation axis of the rotor has a slit extending from at least one of its ends to the longitudinal surface side of the permanent magnet accommodation hole. The embedded permanent magnet electric motor according to claim 3.
The rotor has a flat part near the rotor outer peripheral end of the permanent magnet housing hole that faces the teeth at the tip of the stator slot on a plane perpendicular to the rotation axis. The embedded permanent magnet electric motor according to claim 4, wherein the motor is embedded in the permanent magnet.