JP2010011635A - Rotating electrical machine - Google Patents

Abstract

【Task】
In a rotating electrical machine, a rotating electrical machine that improves the starting characteristics by an end ring shape installed in a rotor is provided.
[Solution]
The present invention relates to a rotating electrical machine having a stator wound with a winding and a rotor, and the rotor includes a squirrel-cage secondary winding and a rotor core, and the rotor core A plurality of through-grooves are provided with a rotor bar, and a plurality of end rings are provided on the axial end surface of the rotor bar. The plurality of end rings have different inner diameters. The rotating electrical machine is characterized in that the radial width is smaller than that of the inner end ring having a small inner diameter.
[Selection] Figure 2

Description

  The present invention relates to a rotating electrical machine using a cage conductor.

  In a squirrel-cage rotor used in a rotating electrical machine, it is common to prepare one end ring outside the rotor core in the axial direction and join it to a rotor bar installed in the rotor core. Patent Document 1 or 2 discloses a configuration for improving noise reduction and steady-state characteristics. Patent Document 3 or 4 discloses a technique for preparing a plurality of end rings. Here, a technique for improving durability at high speed rotation and workability of the rotor is disclosed.

JP-A-9-65626 JP-A-8-149768 Japanese Patent Laid-Open No. 10-52014 Japanese Patent Laid-Open No. 7-231629

  In a rotating electric machine using a squirrel-cage conductor for a rotor, aluminum or copper is used as a material for the squirrel-cage conductor in the prior art. By using such a material with high conductivity, loss in the conductor at the time of rating can be reduced, and high efficiency can be achieved. However, at the time of start-up, several times the current flows in the cage conductor compared to the rated value, but if the material has high conductivity, the resistance is low, so a larger current flows in the conductor and the required power capacity is reduced. growing. Further, the resistance of the squirrel cage conductor and the starting torque are proportional, and because of a phenomenon called proportional transition, the starting torque is reduced and the starting characteristic is deteriorated if the material has high conductivity.

  An object of the present invention is to improve the starting characteristics and maintain the rated characteristics by devising the end ring shape of the rotor.

  In order to solve the above-mentioned problem, in the present invention, among the rotor cage conductors, a plurality of end rings are prepared on one side, and the end ring having the largest inner diameter is the outermost surface in the axial direction of the rotor core. In addition, the non-uniformity of the current density distribution in the end ring during start-up is ensured, and the effective resistance inside the squirrel-cage conductor is increased so that the starting current can be suppressed and at the same time a large starting torque can be obtained. Characterized by structure.

  By making the rotating electrical machine having the rotor of such a structure, the effective resistance in the end ring at the time of starting can be increased, so that the current in the end ring can be suppressed and the starting torque is also large. Therefore, the starting characteristics can be improved. In addition, non-uniformity of the current density distribution in the end ring can be ensured, and the starting characteristics are improved.

  The rotating electrical machine of the present invention is a rotating electrical machine having a stator around which windings are wound, and a rotor, and the rotor has a squirrel-cage secondary winding and a rotor iron core, The rotor core has a rotor bar in a plurality of through-grooves provided in the rotor core, and a plurality of end rings are provided on the end surface in the axial direction of the rotor bar or the rotor core. The plurality of end rings have different inner diameters. The outer end ring having a larger inner diameter has a smaller radial width than the inner end ring having a smaller inner diameter.

  In addition, at least one of the end rings is embedded in the rotor core, or a recess is provided in the axial end surface of the rotor bar or the rotor core, and the end ring is provided in the recess.

  Furthermore, another end ring is provided on the surface of the axial end surface of the rotor core.

  For example, only the end ring located on the outermost peripheral side is provided in the recess, and end rings other than the end ring located on the outermost peripheral side are installed on the surfaces of the axial end surfaces of the rotor bar or the rotor core. It is characterized by being.

  Further, the end ring located on the outermost peripheral side and the axial cross section of the rotor core are flat, the cross section of the inner end ring is shaped to be squeezed in the axial direction, or the cross section is The shape is a curved surface.

  Furthermore, the present invention is characterized in that a permanent magnet is embedded in the rotor core, and the outer diameter of the outer end ring is substantially the same as the outer diameter of the rotor core. And

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

  The present invention improves various characteristics of the rotating electrical machine by the configuration of the rotor of the rotating electrical machine. The rotating electrical machine of the present invention will be described based on examples of embodiments shown in the following drawings.

  1 to 6 show the first embodiment. As shown in FIG. 1, the present embodiment includes a stator 3 including a stator winding 1 and a stator core 2 having the stator winding 1, a rotor bar 21, and an outer end ring. 22, an inner end ring 23, a rotor core 24 having a rotor bar 21, a rotor 7 including a shaft 25, and a stator 3 and a frame 8 for housing the rotor 7.

  At the time of start-up, when current starts to flow through the rotor bar 21 in the rotor core 24, the magnetic flux of the surrounding material is high on the radial inner side of the rotor bar 21, so that the leakage magnetic flux increases and the rotation The leakage reactance becomes larger than the outside of the child bar 21. Therefore, the current flowing in the rotor bar 21 is concentrated near the outer side in the radial direction of the rotor bar 21, hardly flows near the inner side, and the current density distribution is non-uniform in the rotor bar 21. Due to this phenomenon called the skin effect, the effective resistance increases in the rotor bar 21, the starting current decreases, and the starting torque can be increased from the relationship of proportional transition.

  The end ring of the rotor 7 in the present embodiment is constituted by two radially outer outer end rings 22 and inner inner end rings 23 installed at the axial ends of the rotor core 24.

  In this embodiment, two end rings connected to the rotor bar 21 are installed on the inner side and the outer side in the radial direction, but only one end ring of the prior art is connected to the end of the rotor bar, It protrudes beyond the rotor core. For this reason, in the prior art form, the current that is non-uniform in the bar becomes uniform in the end ring and the effective resistance does not increase. However, by preparing two end rings, the current is non-uniform in the rotor bar 21. The current density distribution thus obtained can be maintained, the effective resistance of the squirrel-cage conductor constituted by the outer end ring 22 and the inner end ring 23 can be increased, and the current at the start can be further suppressed. Since more starting torque can be obtained, starting characteristics are improved.

  The outer end ring 22 has a shape whose radial width is thinner than that of the inner end ring 23. Although the current flowing through the rotor bar 21 at the time of starting is concentrated near the outside in the radial direction, the current flowing from the rotor bar 21 flows in the end ring by making the outer end ring 22 thinner than the inner end ring 23. The region can be more limited, the effective resistance in the end ring is increased, the starting current is decreased, and the starting torque is increased.

  2 shows the configuration of the rotor of the rotating electrical machine according to the present embodiment, FIG. 3 is a schematic view of the rotor 7 of FIG. 1 viewed from the axial direction, and FIG. 4 is a cross-sectional view taken along line AA in FIG. 5 is a cross-sectional view taken along the line BB in FIG. 4, and FIG. 6 is a cross-sectional view taken along the line CC in FIG. 3 to 6 are not shown in the drawing for the sake of simplicity.

  As shown in FIG. 4, the rotor core 24 is provided with a recess on the axial surface, and the outer end ring 22 is installed in the recess of the rotor core 24. By installing the outer end ring 22 in the recess, the effect of the skin effect can be obtained even during the start of the outer end ring 22, and non-uniformity of the current inside the end ring can be secured. The effective resistance of the cage conductor constituted by the outer end ring 22 and the inner end ring 23 increases. Further, by installing the inner end ring 23 on the axial surface of the rotor core 24, an increase in leakage reactance at the time of rating is suppressed, and rating characteristics are improved.

  In this embodiment, the inner end ring 23 is installed on the axial surface of the rotor core 24. However, the inner end ring 23 is embedded on the axial surface of the rotor core 24 so that the inner end ring 23 can be turned on at the start. By increasing the leakage reactance in the vicinity of the end ring 23, the influence of the skin effect in the end ring can be further increased, and the starting characteristics can be improved. At this time, the width of the inner end ring 23 in the axial direction may be equal to the height of the concave portion, or may be larger or smaller than that height. When the axial width of the inner end ring 23 is equal to the height of the concave portion, the axial cross section of the rotor by the rotor core 24 and the inner end ring 23 becomes a plane, but when larger than the concave portion, the inner end ring 23 rotates. When it is smaller than the concave portion, it has a shape in which the embedded portion of the inner end ring 23 is recessed.

  As shown in FIG. 4, the outer end ring 22 has an axial end protruding from the end of the rotor core 24, and the outer diameter thereof is equal to the outer diameter of the rotor core 24, and the outer end ring 22 has a diameter equal to that of the outer end ring 22. This serves to prevent the outermost peripheral portion 26 of the rotor cores adjacent in the direction from shifting in the axial direction.

  As shown in FIG. 5, the outer end ring 22 and the inner end ring 23 are provided with holes and grooves that are shaped to fit the rotor bar 21, and the rotor bar 21 is fitted to the outer end ring 22 and the inner end ring 23. After the rotor bar 21 is installed on the rotor core 24, the outer end ring 22 and the inner end ring 23 are installed on the axial side of the rotor core 24. By providing holes and grooves in the outer end ring 22 and the inner end ring 23, the rotor bar 21, the outer end ring 22 and the inner end ring 23 can be joined by brazing, TIG welding, friction stir welding, or the like.

  Since the outermost peripheral portion 26 of the rotor core adjacent to the rotor bar 21 and the outer end ring 22 in the radial direction cannot be integrated with the rotor core 24 by the outer end ring 22, the outermost peripheral portion 26 of the rotor core rotates. There is a risk of idle rotation with respect to the rotation of the child. Therefore, as shown in FIG. 6, the outermost peripheral portion of the rotor core is formed by installing a recess on the inner diameter side of the outermost peripheral portion 26 of the rotor core and fitting a wedge installed on the outer peripheral side of the rotor bar 21. 26 idling is prevented. In this embodiment, the wedge is installed on the rotor bar 21, but it may be installed on the outer end ring 22. Moreover, although the outermost peripheral part 26 of the rotor core is the same as the rotor core 24 laminated with electromagnetic steel sheets, it is not necessarily the same material, and a material such as a massive iron can be used. By using a material such as massive iron, the mechanical strength of the outermost peripheral portion 26 of the rotor core can be increased, and the outer end ring 22 can be prevented from bulging to the outer peripheral side.

  In this embodiment, the rotor bar 21, the outer end ring 22 and the inner end ring 23 are formed by a joining operation, but can also be formed by die casting or two-color molding. By forming by die casting, holes and grooves in the outer end ring 22 and the inner end ring 23 are not required, and the shape of the rotor bar 21 is simplified. Furthermore, by forming by two-color molding, the outer end ring 22 and the inner end ring 23 are formed of different materials while simplifying the shape of the coupling portion of the rotor bar 21, the outer end ring 22 and the inner end ring 23. can do. The material of the outer end ring 22 and the inner end ring 23 is copper, but the outer end ring 22 and the inner end ring 23 can be made of a conductor such as aluminum or brass. The outer end ring 22 can further suppress a current at the time of starting by using a material having a higher resistivity than the inner end ring 23, and can obtain a larger starting torque.

  As the inner end ring 23 moves away from the end of the rotor core 24 in the axial direction, it is possible to reduce the cross-sectional shape. By changing the cross-sectional shape, the current flow at the rated time becomes smooth, and the outer end ring 23 The increase in effective resistance in the inner end ring 23 and the inner end ring 23 can be prevented, and the rated characteristics can be improved. Further, when the cross-sectional shape is narrowed, the flow of current becomes smoother by making the surface a curved surface, and the rated characteristics can be further improved.

  A second embodiment is shown in FIGS. This embodiment differs from the first embodiment in the shape of the rotor core 31 and the outermost outer peripheral portion 36 adjacent to the outermost end ring 32 positioned on the outermost side, and the outermost peripheral portion 36 and the rotor of the rotor core are different. The difference is that there are no wedges in the bar 31 and the outer end ring 32.

  The outermost peripheral portion 36 of the rotor core is fixed to the rotor by shrinkage fitting to prevent the rotor from rotating freely, and there is no wedge, so that the rotor bar 31 and the outermost peripheral portion 36 of the rotor core are manufactured. Becomes easier. Further, by installing the outer end ring 32 so as to be adjacent in the radial direction, the skin effect at the outer end ring 32 can be promoted, and the starting characteristics can be improved.

  A third embodiment is shown in FIGS. The present embodiment differs from the first and second embodiments in the installation position of the end ring, and the rotor core 44 is not provided with a recess, and the outer end ring 42 is installed on the surface of the rotor core 44 in the axial direction. Is different.

  By installing the outer end ring 42 on the surface of the rotor core 44 in the axial direction, the wedge existing in the first embodiment and the shrink-fitting existing in the second embodiment are not necessary, and the manufacturing is facilitated. Further, by installing the outer end ring 42 on the surface of the rotor core 44, the leakage reactance at the time of rating is reduced with respect to the first and second embodiments, and the rated characteristics are improved. In contrast to the prior art, by installing two of the outer end ring 42 and the inner end ring 43, a non-uniform current density distribution in the rotor bar 41 can be maintained, and the effective resistance increases. To improve starting characteristics

  A fourth embodiment is shown in FIGS. This embodiment is different from the first to third embodiments in that a permanent magnet 57 is installed inside the rotor core 54. By installing the permanent magnet 57 on the rotor core 54, the rotational speed of the rotor becomes the synchronous speed at the rated time, the current does not flow to the rotor bar 51, and the copper loss in the rotor bar 51 at the rated time is lost. Is reduced and the rated characteristics are improved.

The figure which shows the structure of the rotary electric machine of this invention. 3 is a three-dimensional cross-sectional view of a rotor of a rotating electrical machine according to Embodiment 1. FIG. FIG. 3 is a side view of the rotor of the rotating electrical machine according to the first embodiment. Sectional drawing between AA in FIG. Sectional drawing between BB in FIG. Sectional drawing between CC in FIG. FIG. 6 is a side view of a rotor of a rotating electrical machine according to a second embodiment. Sectional drawing between AA in FIG. Sectional drawing between BB in FIG. Sectional drawing between CC in FIG. FIG. 6 is a side view of a rotor of a rotating electrical machine according to a third embodiment. Sectional drawing between AA in FIG. Sectional drawing between BB in FIG. FIG. 6 is a side view of a rotor of a rotating electrical machine according to a fourth embodiment. Sectional drawing between AA in FIG. Sectional drawing between BB in FIG. Sectional drawing between CC in FIG.

Explanation of symbols

21 Rotor bar 22 Outer end ring 23 Inner end ring 24 Rotor core 25 Shaft 26 Outermost peripheral part of rotor core

Claims (13)

A rotating electrical machine having a stator wound with windings and a rotor,
In the rotor, a cage secondary winding and a rotor iron core are combined,
A plurality of through-grooves provided in the rotor core have a rotor bar,
A rotating electrical machine comprising a plurality of end rings provided on an axial end surface of the rotor bar or the rotor core.   2. The rotating electrical machine according to claim 1, wherein the plurality of end rings have different inner diameters, and an outer end ring having a larger inner diameter has a smaller radial width than an inner end ring having a smaller inner diameter. .   The rotating electrical machine according to claim 2, wherein at least one of the end rings is embedded in the rotor core.   2. The rotating electrical machine according to claim 1, wherein a concave portion is provided in an axial end surface of the rotor bar or the rotor core, and the end ring is provided in the concave portion.   2. The rotating electrical machine according to claim 1, wherein the end ring is provided on a surface of an axial end surface of the rotor bar or the rotor core.   Only the end ring located on the outermost peripheral side is provided in the recess, and end rings other than the end ring located on the outermost peripheral side are installed on the surfaces of both end surfaces in the axial direction of the rotor bar or the rotor core. The rotating electric machine according to claim 4, wherein the rotating electric machine is provided.   The rotating electrical machine according to claim 2, wherein the end ring located on the outermost peripheral side and the axial cross section of the rotor core are flat.   The rotating electrical machine according to claim 2, wherein a cross section of the inner end ring is shaped to be narrowed in an axial direction.   The rotating electrical machine according to claim 2, wherein a cross section of the inner end ring has a curved surface.   The rotating electrical machine according to claim 1, wherein a permanent magnet is embedded in the rotor core.   The rotating electrical machine according to claim 2, wherein an outer diameter of the outer end ring is substantially the same as an outer diameter of the rotor core.   The rotating electric machine according to claim 2, wherein the end ring includes a conductive material.   The rotating electrical machine according to claim 12, wherein the outer end ring is made of a material having a higher resistance than the inner end ring.

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