JP5238298B2 - Permanent magnet synchronous motor - Google Patents

Description

  The present invention relates to a permanent magnet synchronous motor used for a railway vehicle such as a Shinkansen.

  As a train driving motor, a self-ventilated cooling induction motor is generally known (for example, Patent Document 1).

  FIG. 5 is an axial sectional view of such a conventional induction motor.

  As shown in FIG. 5, a cylindrical stator core 22 is fixed to the inner peripheral surface of the frame 21. A large number of slots are formed on the inner circumference side of the stator core 22 at equal intervals on the circumference, and stator coils 23 are accommodated in these slots, respectively. These constitute a stator.

  Further, both ends of the frame 21 are attached to the bearing bracket 25 via brackets 24. The bearing bracket 25 has a bearing 26, and the bearing 26 supports a rotor shaft 27 in a freely rotatable manner.

  A rotor core 28 formed in a cylindrical shape by laminating silicon steel plates is attached to the center portion of the rotor shaft 27 with iron core retainers 29 disposed at both ends thereof. Slots are formed on the outer periphery of the rotor core 28 at equal intervals on the circumference, and the rotor bars 30 are respectively stored in these slots. Both end portions of each rotor bar 30 protrude from the slot of the rotor core 28 and are integrally connected by an end ring. These constitute a rotor.

The rotor core 28, a plurality of vent holes 31 which penetrates axially exist at regular intervals on a circumference apart appropriately from the center of the rotor shaft 27 as shown in FIG. 6 are al provided. A ventilation fan (not shown) is attached to one bearing side of the rotor shaft 27, and cooling air is provided by the ventilation fan to the rotor core 28, the inner surface of the stator core 22, and the rotor core. The air is exhausted to the outside through an air outlet provided in the frame 21 through a gap with the outer surface of 28.

  However, since the induction motor having such a structure can secure mechanical strength, it can withstand high-speed rotation, but has a difficulty in reducing the weight, and a circle appropriately separated from the center of the rotor shaft 27. The rotor core 28 is cooled by allowing cooling air to flow through a plurality of ventilation holes 31 provided in a row on the circumference. However, the ventilation of the gap between the inner surface of the stator core 22 and the outer surface of the rotor core 28 is performed. When the opening area of the ventilation hole 31 is adjusted by the iron core retainer 29 in order to increase the amount, the cooling performance of the rotor iron core 28 is deteriorated.

  Recently, as a motor for high-speed rotation mounted on a railway vehicle such as a Shinkansen, a permanent magnet synchronous motor having a structure capable of reducing the weight and improving the cooling performance has been adopted.

  By the way, there exists a thing as shown in FIG. 7 as a permanent-magnet synchronous motor (for example, patent document 2).

  FIG. 7 is a radial sectional view of a rotor in a permanent magnet synchronous motor, which is coaxially disposed with a stator having an armature coil (not shown) with a small gap, and is rotatable by a bearing via a rotating shaft 41a. The rotor 41 supported on the rotor core 42 is provided along a side surface of a rotor core 42 formed by laminating silicon steel plates into a cylindrical shape, and the core portion of the rotor core 42 serving as the magnetic pole 43a. The permanent magnet 45 is inserted into a radially elongated cavity 44 arranged in a V shape. In this case, the cavity 44 is processed by punching a silicon steel plate.

According to the permanent magnet synchronous motor having such a configuration, the permanent magnet 45 provided between the magnetic poles is magnetized substantially in the circumferential direction, and suppresses magnetic flux leaking to the iron core portion between the magnetic poles 43a and the side surfaces of the magnetic pole 43a. It is possible to increase the effective magnetic flux and obtain a high output. At the same time, it can be firmly fixed by embedding the permanent magnet 45 in the cavity 44 surrounded by the rotor core 42, so that it can sufficiently withstand high speed rotation.
JP 2000-152561 A Japanese Patent No. 3170224

  However, although the permanent magnet synchronous motor having the above-described configuration can obtain high output and can withstand high-speed rotation, it is necessary to further improve the ventilation structure and reduce the weight particularly in order to adopt it as a vehicle motor.

  The present invention has been made in view of the above demands, and provides a permanent magnet synchronous motor capable of improving cooling performance and reducing weight while ensuring the mechanical strength of a rotor core against centrifugal force. The purpose is to do.

In order to achieve the above object, the present invention provides a stator having a stator coil on the inner peripheral side of the stator core, and a plurality of magnetic poles by inserting a permanent magnet into a cavity provided in the longitudinal direction of the rotor core. The parts are formed at equal intervals in the circumferential direction, and air holes for ventilation cooling are provided in the longitudinal direction of the rotor core, and portions corresponding to the air holes are formed on both end surfaces in the longitudinal direction of the rotor core. A magnetic shield plate having a hole and a rotor having an iron core presser disposed therein, and the air holes provided in the rotor iron core are on a circle having a diameter D1 centered on the rotation center and a diameter D2 larger than the diameter D1. When the circle is drawn, the first air hole having the center at the intersection of the circle with the diameter D1 and the magnetic pole center line, and the second having the center at the intersection with the circle with the diameter D2 and the center line between the magnetic poles. The number of poles is arranged as each of the air holes , and the stator iron In consideration of the balance between the gap between the inner peripheral surface of the core and the outer peripheral surface of the rotor core and the ventilation balance of the bypass duct, a portion of the first and second air holes are introduced into the intake or exhaust side of the magnetism. The hole of the corresponding part of at least one of the shielding plate or the iron core presser is closed .

  According to the present invention, it is possible to improve the cooling performance and reduce the weight while ensuring the mechanical strength of the rotor core against centrifugal force.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an axial sectional view showing a first embodiment of a permanent magnet synchronous motor according to the present invention, and FIG. 2 is an enlarged radial sectional view showing a part of a rotor core in the same embodiment.

  In FIG. 1, reference numeral 1 denotes a frame, and a cylindrical stator core 2 is fixed to the inner peripheral surface of the frame 1. A large number of slots are formed on the inner circumference side of the stator core 2 at equal intervals on the circumference, and the stator coils 3 are accommodated in these slots, respectively. These constitute a stator.

  Further, bearing brackets 5 are attached to both ends of the frame 1 via brackets 4. The bearing bracket 5 has a bearing 6, and the bearing 6 supports a rotor shaft 7 so as to be rotatable.

  A rotor core 8 formed in a cylindrical shape by laminating silicon steel plates is attached to the central portion of the rotor shaft 7 through a key groove 9, and magnetic shielding plates 10 are brought into contact with both end faces of the rotor core 8. Are fixed integrally with the iron core presser 11. In this case, the key groove 9 is mounted so that the center position thereof coincides with a center line between magnetic poles described later. These constitute a rotor.

  In such a rotor, as shown in FIG. 2, the rotor core 8 is inclined at a predetermined angle from the circumferential side toward the iron core portion as a magnetic pole portion formed at equal intervals in the circumferential direction. The hollow portions 12 having a substantially elliptical cross section are provided so as to be V-shaped, and the permanent magnets 13 are embedded in the hollow portions 12 so that the magnetic poles 8a are formed in the iron core portions between the permanent magnets 13 arranged in the V-shape. Form.

  Further, in the rotor core 8, a circle having a diameter D1 having the center O of the rotor shaft 7 as the center O and a circle having a diameter D2 larger than the diameter D1 are drawn on the iron core, and the circle having the diameter D1 and the magnetic pole center line are drawn. (Line connecting the center O and the center of the magnetic pole) The first air holes 14 having the center at the intersection with L1 are provided by the number of poles, and the circle having the diameter D2 and the center line between the magnetic poles (the center position of the key groove and the magnetic pole) A line connecting the centers between each other) The second air holes 15 having the center at the intersection with L2 are provided by the number of poles.

  In this case, the illustrated dimension B between the second air hole 15 and the illustrated dimension C between the first air hole 14 and the illustrated dimension C between the magnetic pole center line and the permanent magnet 13 arranged in a V shape is illustrated. The diameters D1 and D2 and the air hole diameter are determined so as to be approximately equal to A. That is, the shortest distance C between the first air hole 14 and the permanent magnet 13 and the shortest distance B between the second air hole 15 and the permanent magnet 13 are substantially the same as the shortest distance A between the center line L2 between the magnetic poles and the permanent magnet 13. Thus, the diameters of the first air hole 14 and the second air hole 15 are determined.

  Further, the diameter of the first air hole 14 and the diameter of the second air hole 15 may be different, but the diameters of the air holes provided in the same row need to be the same. This is to prevent the occurrence of weight imbalance and magnetic pole imbalance.

  The cavity 12, the first air hole 14, and the second air hole 15 are processed by punching a silicon steel plate in advance.

  On the other hand, the magnetic shielding plate 10 and the iron core retainer 11 that are in contact with both end faces of the rotor iron core 8 are provided with holes communicating with these air holes corresponding to the first air holes 14 and the second air holes 15. ing.

  As described above, according to the first embodiment, a circle with a diameter D1 having a diameter D1 larger than the diameter D1 and a circle with a diameter D1 centered on the center O of the rotor shaft 7 are drawn on the iron core portion. The first air holes 14 having the center at the intersection of the magnetic pole center line L1 and the number of poles are provided, and the second air holes 15 having the center at the intersection of the circle having the diameter D2 and the magnetic pole center line L2 are provided as poles. The illustrated dimension B between the second air hole 15 and the illustrated dimension C between the first air holes 14 with respect to the permanent magnets 13 provided in the number of V-shaped is the center line between the magnetic poles. The diameters D1 and D2 and the air hole diameter are determined so as to be substantially equal to the illustrated dimension A.

Therefore, important in securing the width of the core portion between the first and second air hole 15 and between the first and second air holes 14, 15 and the permanent magnet 1 3, and to improve the saliency Since the total area of the air holes can be increased while securing the magnetic path in the q-axis direction (direction between the magnetic poles), the cooling performance can be improved and the weight can be reduced.

  By the way, in the case of an induction motor, the ventilation holes provided in the rotor core are symmetrical with respect to the magnetic poles formed by the rotor bars on the circumference of the rotor core. Even if it is provided, magnetic imbalance does not occur. However, in the case of a permanent magnet synchronous motor, a permanent magnet is embedded in a V-shaped cavity provided in the rotor core, and the core portion between these permanent magnets is embedded. Since the magnetic poles are formed on the surface, if the air holes are provided only for the purpose of reducing the weight, there is a possibility that magnetic imbalance occurs and the cooling performance is lowered due to magnetic saturation.

In this embodiment, define the position and size of the first air hole 14 and the second air hole 15 provided in the rotor core 8 as described above, the cooling performance due to magnetic saturation caused magnetic unbalance It is possible to reduce the weight without lowering.

  Furthermore, when it is necessary to adjust the ventilation amount in consideration of the ventilation balance between the gap between the inner surface of the stator core 2 and the outer surface of the rotor core 8 and the bypass duct, both end surfaces of the rotor core 8 As shown in FIG. 3, a hole 10a corresponding to the first air hole 14 or the second air hole 15 of the magnetic flux shielding plate 10 provided to prevent leakage magnetic flux in the axial direction is appropriately closed. Thus, the gap air volume between the inner surface of the stator core 2 and the outer surface of the rotor core 8 can be adjusted.

  Further, as shown by a dotted line in FIG. 4, the hole 10a of the magnetic flux magnetic shielding plate 10 corresponding to the first air hole 14 on the inner diameter side, which is far from the permanent magnet 13 and has a low peripheral speed, is appropriately closed, so that The gap air volume can be adjusted without impairing the cooling.

  In the above description, the hole portion of the magnetic flux magnetic shielding plate 10 is closed. However, the hole portion of the iron core retainer 11 may be closed, and the hole portions of both the magnetic flux magnetic shielding plate 10 and the iron core retainer 11 may be appropriately closed. However, the gap air volume can be adjusted in the same manner as described above.

  On the other hand, when the center position of the key groove 9 is made coincident with the center line of the magnetic pole 8a as shown by the dotted line in the figure, the iron core width D between the key groove 9 and the first air hole 14 is reduced, and mechanical force against centrifugal force is reduced. Although there is a problem in securing the strength, in this embodiment, when the rotor core 8 is mounted on the rotor shaft 7, the center position of the key groove 9 is made to coincide with the center line between the magnetic poles 8a. Therefore, it is possible to prevent the iron core width between the magnetic pole center key groove 9 and the first air hole 14 from being reduced, and to ensure the mechanical strength of the rotor iron core 8 against centrifugal force.

  The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention.

1 is an axial sectional view showing a first embodiment of a permanent magnet synchronous motor according to the present invention. Radial direction sectional drawing which expands and shows a part of rotor core in the same embodiment. The figure which shows the state by which the hole part of the magnetic flux magnetic shielding board corresponding to the 1st and 2nd air hole of the rotor core in the same embodiment was block | closed suitably. The figure which shows the state by which the hole part of the magnetic flux magnetic shielding board corresponding to the 1st air hole of the rotor core in the same embodiment was plugged up suitably. An axial direction sectional view showing an example of the conventional induction motor. Radial direction sectional drawing which expands and shows a part of rotor core in the same induction motor. Radial direction sectional drawing of the rotor of the conventional permanent magnet rotary electric machine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Frame, 2 ... Stator iron core, 3 ... Stator coil, 4 ... Bracket, 5 ... Bearing bracket, 6 ... Bearing, 7 ... Rotor shaft, 8 ... Rotor iron core, 8a ... Magnetic pole part, 9 ... Keyway, DESCRIPTION OF SYMBOLS 10 ... Magnetic shielding board, 11 ... Iron core retainer, 12 ... Hollow part, 13 ... Permanent magnet, 14 ... 1st air hole, 15 ... 2nd air hole

Claims (4)

A stator having a stator coil on the inner peripheral side of the stator core, and a permanent magnet inserted into a cavity provided in the longitudinal direction of the rotor core, a plurality of magnetic pole portions are spaced at equal intervals in the circumferential direction. A magnetic shield plate and a core presser having a hole for cooling cooling in the longitudinal direction of the rotor core, and having holes at both ends of the rotor core in the longitudinal direction corresponding to the air holes. With the arranged rotor,
When the air hole provided in the rotor core is drawn on a circle having a diameter D1 centered on the rotation center and a circle having a diameter D2 larger than the diameter D1, the air hole is formed between the circle having the diameter D1 and the magnetic pole center line. A first air hole having a center at the intersection and a second air hole having a center at the intersection of the circle having the diameter D2 and the center line between the magnetic poles are arranged by the number of poles, respectively , and the inner peripheral surface of the stator core In consideration of the balance between the gap between the outer peripheral surface of the rotor core and the outer periphery of the rotor core and the ventilation balance of the bypass duct, the magnetic shielding plate or the iron core on the intake or exhaust side of a part of the first and second air holes A permanent magnet synchronous motor characterized by closing a hole in a corresponding portion of at least one of the pressers . In the permanent magnet synchronous motor according to claim 1,
The first air hole so that the shortest distance between the first air hole and the permanent magnet and the shortest distance between the second air hole and the permanent magnet are substantially the same as the shortest distance between the center line between the magnetic poles and the permanent magnet. And a permanent magnet synchronous motor, wherein the diameters of the second air holes are respectively determined. In the permanent magnet synchronous motor according to claim 1 ,
The least hole for closing even while the magnetic shielding plate or the core pressing the permanent magnet synchronous motor, which is a hole corresponding to the first air hole. In the permanent magnet synchronous motor according to any one of claims 1 to 3 ,
A permanent magnet synchronous motor characterized in that a center position of a key groove when the rotor core is mounted on a shaft is the center line between the magnetic poles.

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