JP2011078225A - Permanent magnet synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permanent magnet synchronous motor reducing leakage magnetic flux in a rotor shaft direction and improving characteristics. <P>SOLUTION: The motor is provided with a rotation shaft which is rotatably supported, a cylindrical rotor core which is fitted to the rotation shaft and can be rotated integrally with the rotation shaft, a permanent magnet fitted to the rotor core, pressing plates which are fitted to the rotation shaft and presses both ends in the shaft direction of the rotor core, magnetic shielding plates facing each other at both ends of the shaft direction of the rotor core and positioned between the rotor core and the pressing plate, and a stator core facing the permanent magnet and installed coaxially with the rotor core. The pressing plate is formed in a position overlapping the rotation shaft direction at a part below a center line of the permanent magnet. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electric motor used for a railway vehicle such as a Shinkansen, and more particularly to a permanent magnet synchronous motor in which a permanent magnet for a field is provided on a rotor.

  2. Description of the Related Art A vehicle drive device, for example, a railroad vehicle drive device includes a plurality of main motors installed in a carriage in the vicinity of wheels and a control device that drives these main motors. In recent years, permanent magnet synchronous motors have come to be applied as main motors due to advances in technology for improving magnet performance and increasing magnetic flux density. In this case, the main motor and the control device that supplies power correspond to 1: 1. Therefore, the control device can be installed in the vicinity of each main motor or integrated with the main motor.

  A permanent magnet synchronous motor, for example, an inner rotor type permanent magnet synchronous motor, generally includes a cylindrical rotor core attached to a rotating shaft, and a stator core disposed around the rotor core. ing. Both end portions in the axial direction of the rotor core are pressed by an iron core pressing plate attached to the rotating shaft and positioned at predetermined positions. A plurality of permanent magnets are attached to the rotor core.

  Patent Document 1 describes a reluctance type rotating electrical machine in which a plurality of permanent magnets are arranged in a hollow portion provided inside a rotor core along the rotation axis direction.

JP-A-11-27913

  However, in the configuration of the rotating electrical machine described in Patent Document 1, leakage magnetic flux in the rotation axis direction that could not be suppressed by the magnetic shielding plate is induced to the iron core pressing plate. Therefore, there exists a problem that the characteristic of a rotary electric machine falls.

  In view of the above, an object of the present invention is to provide a permanent magnet synchronous motor that can alleviate leakage magnetic flux in the direction of the rotation axis and improve characteristics.

  A permanent magnet synchronous motor according to the present invention includes a rotary shaft that is rotatably supported, a cylindrical rotor core that is attached to the rotary shaft and can rotate integrally with the rotary shaft, and is attached to the rotor core. Permanent magnets, presser plates attached to the rotary shaft and holding axially opposite ends of the rotor core, respectively, and opposed to both axial ends of the rotor core, respectively, and the rotor A magnetic shielding plate positioned between an iron core and the presser plate, and a stator iron core provided to face the permanent magnet and coaxially with the rotor iron core, the presser plate Is formed at a position overlapping with the rotation axis direction below the center line of the permanent magnet.

  According to the present invention, the amount of magnetic flux flowing to the stator core is increased by reducing leakage of magnetic flux induced outside the rotor core direction and the rotor core while ensuring the mechanical strength of the rotor core. Can be improved.

The longitudinal cross-sectional view which showed only the upper part from the rotation center of the permanent-magnet synchronous motor which concerns on the 1st Embodiment of this invention. The top view of the axial direction of the rotor core in the permanent magnet synchronous motor which concerns on the 1st Embodiment of this invention. The top view of the axial direction of the iron core retainer board in the permanent-magnet synchronous motor which concerns on the 1st Embodiment of this invention. The top view of the axial direction of the iron core pressing board in the permanent-magnet synchronous motor which concerns on the 2nd Embodiment of this invention. The top view of the axial direction of the iron core retainer board in the permanent-magnet synchronous motor which concerns on the 3rd Embodiment of this invention. The graph which shows magnetic flux distribution in the permanent-magnet synchronous motor which concerns on the 1st Embodiment and 3rd Embodiment of this invention. The top view of the axial direction of the rotor core in the conventional permanent magnet synchronous motor.

  Hereinafter, a permanent magnet synchronous motor according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of a permanent magnet synchronous motor 10 according to the first embodiment, and shows an upper part from the center of rotation. FIG. 2 is a plan view of the rotor core 18 in the axial direction in the first embodiment.

  As shown in FIG. 1, the permanent magnet synchronous motor 10 includes a substantially cylindrical frame 12 that is closed at both ends, and a rotating shaft 14 that is provided substantially through the frame 12 coaxially. Bearing brackets 15 are attached to both ends of the frame 12 via brackets 13. Both end portions of the rotary shaft 14 are supported by bearings 16 so as to be rotatable with respect to the bearing bracket 15. One end of the rotating shaft 14 protrudes outward from the frame 12 and constitutes an output end 14a.

  As shown in FIGS. 1 and 2, in the frame 12, a cylindrical rotor core 18 is coaxially fixed at the center in the axial direction of the rotating shaft 14. The rotor core 18 that functions as a rotor is configured by laminating a large number of annular metal plates made of a magnetic material, for example, a silicon steel plate.

  An annular magnetic shielding plate 20 made of, for example, stainless steel is provided in close contact with both axial end surfaces of the rotor core 18. Each magnetic shielding plate 20 is formed in the same diameter as the rotor core 18. The rotor core 18 is sandwiched from both sides in the axial direction by a pair of iron core pressing plates 22 fixed to the rotating shaft 14, and is supported and positioned at a predetermined position. Each magnetic shielding plate 20 is located between the rotor iron core 18 and the iron core holding plate 22. The rotor iron core 18, the magnetic shielding plate 20, and the iron core holding plate 22 constitute a rotor. The magnetic shielding plate 20 reduces leakage of magnetic flux to both side surfaces of the rotor core 1 in the axial direction.

  The iron core holding plate 22 is made of a magnetic material or a nonmagnetic material. Each iron core pressing plate 22 is formed in an annular shape, and its outer diameter is slightly smaller than the outer diameter of the rotor iron core 18. The iron core holding plate 22 firmly fixes the rotor iron core 18 and the permanent magnet 24 to the rotating shaft 14 even when the rotor iron core 18 rotates at a high speed. The shape of the iron core holding plate 22 will be described in detail later.

  The rotor core 18 is provided with a plurality of field permanent magnets 24. Each permanent magnet 24 is formed in an elongated plate shape and is embedded in a cavity 28 formed on the outer periphery of the rotor core 18. The cavity 28 is processed by punching the rotor core 18.

  As shown in FIG. 2, the cavity 28 is formed on the rotor core 18, which is a magnetic pole formed at equal intervals in the circumferential direction of the rotor core 18, from the outer periphery side of the rotor core 18. Inclined by a predetermined angle toward the iron core 18 and provided in a V shape. The magnetic pole is formed on the outer peripheral side of the rotor core 18 by a permanent magnet 24 provided in a V shape.

  A permanent magnet 24 is embedded in each cavity 28. The cross section of the permanent magnet 24 in the axial direction is rectangular. The permanent magnet 24 has a long side from the outer peripheral side of the rotor core 18 toward the rotor core 18. Six sets of two permanent magnets 24 are provided at equal intervals in the circumferential direction of the rotor core 18 as one set. The rotor core 18 is formed with magnetic poles 18a, 18b, 18c, 18d, 18e, and 18f.

  Each permanent magnet 24 extends along the axial direction of the rotary shaft 14, and its axial length is formed to be equal to the axial length of the rotor core 18. Each permanent magnet 24 is arranged in a state where both axial ends thereof coincide with both axial ends of the rotor core 18. The plurality of permanent magnets 24 are arranged at predetermined intervals in the circumferential direction of the rotor core 18. The permanent magnet 24 is not limited to the configuration embedded in the rotor core 18 and may be configured to be affixed to the outer peripheral surface of the rotor core.

  As shown in FIG. 1, a cylindrical stator core 30 is provided on the outer peripheral side of the rotor core 18 via a minute air gap (air gap). The stator core 30 is fixed to the inner peripheral surface of the frame 12 and is arranged coaxially with the rotor core 18. The stator core 30 is formed by laminating a large number of annular metal plates made of a magnetic material, for example, a silicon steel plate. A plurality of slots (not shown) extending in the axial direction are formed in the inner peripheral portion of the stator core 30, and the stator coil 32 is embedded in these slots. The coil ends of the stator coil 32 protrude in the axial direction from both end surfaces of the stator core 30. The stator core 30 and the stator coil 32 constitute a stator.

  An outer surface of the bracket 13 is provided with a pedestal (not shown) for attaching the permanent magnet synchronous motor 10 to, for example, a carriage frame of an electric vehicle, and an attachment seat 34 for connecting to other equipment.

  Next, the shape of the iron core pressing plate 22 in the permanent magnet synchronous motor 10 according to the first embodiment will be described. The iron core retainer plate 22 shown in FIG. 3 according to the first embodiment has a shape in which a part of the iron core retainer plate 22 shown in FIG. 7 is cut away. The iron core retainer plate 22 in FIG. 7 has an outer diameter larger than the radial position where the permanent magnets 24 are provided, and the outermost peripheral portion thereof overlaps the permanent magnets 24 in the axial direction.

  Next, with reference to FIG. 2, a description will be given of a portion cut out from the core presser plate 22 shown in FIG. Henceforth, in description of the positional relationship of the rotor iron core 18, the iron core holding plate 22, and the permanent magnet 24, it means that each corresponds to an axial direction.

  2 is a detailed plan view of the iron core holding plate 22 shown in FIG. A center line between the adjacent permanent magnets 24 constituting the mutual magnetic poles adjacent to each other in the circumferential direction (the magnetic pole 18a and the magnetic pole 18b) is defined as L1. Similarly, the center line between the adjacent permanent magnets 24 constituting the magnetic poles adjacent in the circumferential direction (the magnetic pole 18a and the magnetic pole 18f) is L2. A line segment passing through the center line between the permanent magnets 24 constituting the magnetic pole 18a and the contact point on the outer periphery of the rotor core 18 is defined as L3.

  Assume that the intersections of L1 and L3 and L2 and L3 are C1 and C2, respectively. When a parallel line L4 is drawn from the intersection C1 at an angle θ that is the same as the angle of inclination of the permanent magnet 24, L4 becomes permanent in parallel with the side from the outer peripheral side of the rotor core 18 of the permanent magnet 24 into the rotor core 18. It becomes a center line that bisects the cross section of the magnet 24. Similarly, when a parallel line L5 is drawn from the intersection C2 at an angle θ that is the same as the angle inclination of the permanent magnet 24, L5 is a side extending from the outer peripheral side of the rotor core 18 of the permanent magnet 24 into the rotor core 18. It becomes a center line that bisects the cross section of the permanent magnet 24 in parallel.

  The intersection of L4 and the outer periphery of the iron core presser plate 22 is defined as a1. Let the intersection of L5 and the outer periphery of the iron core pressing plate 22 be a2. Let b be the intersection of L4 and L5. The iron core retainer plate 22 in the first embodiment shown in FIG. 3 has an arc-shaped outer edge from a1 to a2 of the iron core retainer plate 22 shown in FIG. 7, and a line segment passing through a1 and b and a line passing through b and a2. Cut out the substantially fan-shaped part so that it becomes the outer edge connected in minutes. It is also possible to change the shape of the corners at a1, a2, and b of the iron core holding plate 22. The same applies to adjacent permanent magnets 24 constituting the magnetic poles 24b, 24c, 24d, 24e, and 24f.

  That is, the iron core retainer plate 22 is formed on the rotor core 18 more than the center line that bisects the cross section of the permanent magnet 24 in parallel with the side from the outer peripheral side of the rotor core 18 of the permanent magnet 24 into the rotor iron core 18. It is a shape that does not overlap the permanent magnet 24 in the axial direction on the outer peripheral side.

  Here, FIG. 6 shows the magnetic flux distribution in the axial direction between the minute gaps between the rotor core 18 and the stator core 30 of the permanent magnet synchronous motor 10 shown in FIG. The horizontal axis indicates the position from one end side to the other end side in the axial direction of the rotor core 18. The vertical axis represents the magnetic flux density between the minute gaps.

  Compared to the case where the iron core holding plate 24 having the shape shown in FIG. 7 is used in the permanent magnet synchronous motor 10, it is finer to use the iron core holding plate 24 in the first embodiment shown in FIG. It can be confirmed that the magnetic flux passing between the gaps is increased.

  Therefore, according to the first embodiment, the iron core holding plate 22 does not disturb the magnetic field generated in the rotor iron core 18. Furthermore, in order to reduce the leakage of magnetic flux induced in the axial direction and out of the rotor core 18 while ensuring the mechanical strength of the rotor core 18, the amount of magnetic flux flowing to the stator core 30 increases, and the permanent magnet synchronous motor Ten characteristics can be improved.

  Here, the axial length of the rotor core 18 is slightly longer than the axial length of the stator core 30, and both axial ends of the rotor core 18 project outward beyond both axial ends of the stator core. By doing so, the shortage of magnetic flux in the vicinity of the end of the rotor core can be minimized. As a result, it is possible to suppress a decrease in magnetic flux in the vicinity of the axial end of the rotor core and to improve the performance of the electric motor. Also in this case, according to the first embodiment, it is possible to reduce magnetic flux leakage through the iron core holding plate 22 and improve the characteristics of the electric motor.

  Next, a permanent magnet synchronous motor 10 according to another embodiment of the present invention will be described.

  FIG. 4 is a plan view in the axial direction of the rotor core 18 and the iron core retainer plate 22 in the second embodiment.

  As shown in FIG. 4, according to the permanent magnet synchronous motor 10 according to the second embodiment, the iron core pressing plate 22 is the shortest of the positions where the permanent magnets 24 are provided from the center position of the rotor iron core 18. The circular cross-sectional shape has an outer diameter smaller than the radial position. That is, the iron core retainer plate 22 has a shape in which the outer periphery of the iron core retainer plate 22 does not overlap the permanent magnet 24 in the axial direction.

  The iron core holding plate 22 may have a shape in which the outer diameter D2 of the iron core holding plate 22 is equal to or less than the distance D3 from the center position of the rotor iron core 18 to the intersection b as shown in FIG. The core pressing plate 22 may have a shape that overlaps the permanent magnet 24 in the axial direction as long as the outer periphery of the core pressing plate 22 does not overlap the parallel lines L4 and L5 of the permanent magnet 24 shown in FIG.

  In the second embodiment, other configurations are the same as those in the first embodiment, and the same operational effects as those in the first embodiment can be obtained.

  FIG. 5 is a plan view of the rotor iron core 18 and the iron core retainer plate 22 in the axial direction according to the third embodiment. A straight line connecting positions where the distances from the center position of the rotor core 18 to each of the two permanent magnets 24 constituting the magnetic pole 18a are minimum is L6. L3 and L4, which are the center lines of the permanent magnet 24, are translated so as to approach the center position of the rotor core 18, and straight lines in contact with the sides (or points) of the permanent magnet 24 are denoted as L7 and L8, respectively.

  According to the permanent magnet synchronous motor 10 according to the third embodiment, the iron core holding plate 22 is surrounded by L6, L7, L8 and the outer periphery of the rotor core 18, and does not include the center position of the rotor core 18. The shape does not overlap in the axial direction. The same applies to the adjacent permanent magnets 24 constituting the magnetic poles 18b, 18c, 18d, 18e, and 18f, respectively. Between the permanent magnets 24 adjacent to each other in the magnetic poles adjacent to each other in the circumferential direction, the outer edge of the iron core pressing plate 22 approaches the outer periphery of the rotor iron core 18 so as not to overlap the permanent magnet 24 in the axial direction on L1. To expand.

  As shown in FIG. 6, compared with the case where the iron core holding plate 24 having the shape shown in FIG. 7 is used in the permanent magnet synchronous motor 10, the iron core holding plate 24 in the third embodiment shown in FIG. It can be confirmed that the magnetic flux passing between the minute gaps is increased in the case of using 10. When the iron core holding plate 24 in the third embodiment is used, the amount of magnetic flux is the same as that in the case of using the iron core holding plate 24 in the first embodiment.

  The iron core holding plate 24 may be surrounded by L4, L5, L6 and the outer periphery of the rotor core 18, and may not have a shape that does not overlap in the axial direction with a portion not including the center position of the rotor core 18.

  In the third embodiment, other configurations are the same as those of the first embodiment, and the same operational effects as those of the first embodiment can be obtained. Furthermore, since the area facing the rotor core 18 of the iron core pressing plate 22 can be increased, the mechanical strength of the rotor core 18 with respect to the rotating shaft 14 is increased.

  The present invention is not limited to the above-described embodiment, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. Some constituent elements may be deleted from all the constituent elements shown in the embodiments, or constituent elements over different embodiments may be appropriately combined.

  The permanent magnet synchronous motor according to the present invention is not limited to a motor for a vehicle drive device, but can be applied to various rotary motors such as an automobile motor, an industrial motor, and a generator. The material, dimensions, and the like of the constituent elements of the permanent magnet synchronous motor are not limited to the above-described embodiments, and can be variously selected as necessary. The permanent magnet synchronous motor is applicable not only to the inner rotor type but also to the outer rotor type.

  DESCRIPTION OF SYMBOLS 10 ... Permanent magnet synchronous motor, 14 ... Rotating shaft, 18 ... Rotor iron core, 20 ... Magnetic shielding board, 22 ... Iron core pressing board, 24 ... Permanent magnet, 30 ... Stator iron core.

Claims (4)

A rotating shaft supported rotatably,
A cylindrical rotor core attached to the rotary shaft and rotatable integrally with the rotary shaft;
A permanent magnet attached to the rotor core;
A presser plate attached to the rotary shaft and holding both axial ends of the rotor core;
A magnetic shielding plate provided opposite to both axial ends of the rotor core, each positioned between the rotor core and the presser plate;
A stator core provided to face the permanent magnet and coaxially with the rotor core, and
The permanent magnet synchronous motor according to claim 1, wherein the presser plate is formed at a position overlapping with the rotation axis direction below the center line of the permanent magnet.   The permanent magnet synchronous motor according to claim 1, wherein the presser plate is formed at a position that does not overlap the permanent magnet in the direction of the rotation axis.   A plurality of the permanent magnets are attached in the circumferential direction of the rotor core, and between the adjacent permanent magnets constituting adjacent magnetic poles, the presser plate overlaps the rotation axis direction in the vicinity of the outer periphery of the rotor core. The permanent magnet synchronous motor according to claim 1, wherein the permanent magnet synchronous motor is formed as follows.   The permanent magnet synchronous motor according to claim 1, wherein the magnetic shielding plate has a variable thickness in the rotation axis direction.

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