阅读说明：本技术 笼型感应旋转电机、块状转子以及笼型感应旋转电机的设计方法 (Cage-type induction rotating machine, block rotor, and method for designing cage-type induction rotating machine ) 是由 坪井雄一 栗田聪 米谷晴之 笹井拓真 于 2017-12-12 设计创作，主要内容包括：笼型感应旋转电机具备块状转子、定子以及轴承。块状转子具有轴部、与其一体地形成有转子槽(14)的圆柱状的转子铁心部(13)及在转子铁心部(14)内贯通且在转子铁心部(13)的轴向的两外侧相互结合的多个导体条(16)。定子具有设置在转子铁心部(13)的径向外侧的圆筒状的定子铁心(21)和在其径向的内侧表面在周向上相互隔开间隔地形成且贯通在轴向上延伸的多个定子槽(22)的内部的定子绕组。转子槽(14)的外侧壁(14a)、内侧壁(14b)相对于轴部的包括旋转轴的平面倾斜规定的角度以上。(A cage-type induction rotating machine is provided with a block rotor, a stator, and a bearing. The block-shaped rotor has a shaft portion, a cylindrical rotor core portion (13) in which rotor grooves (14) are formed integrally therewith, and a plurality of conductor bars (16) which penetrate through the rotor core portion (14) and are joined to each other on both outer sides of the rotor core portion (13) in the axial direction. The stator includes a cylindrical stator core (21) disposed radially outside the rotor core portion (13), and a stator winding formed on the radially inner surface thereof at intervals in the circumferential direction and penetrating the inside of a plurality of stator slots (22) extending in the axial direction. The outer wall (14a) and the inner wall (14b) of the rotor groove (14) are inclined at a predetermined angle or more with respect to a plane including the rotation axis of the shaft.)

1. A cage-type induction rotating machine is characterized by comprising:

a block rotor having: a shaft portion extending in an axial direction and rotatably supported; a cylindrical rotor core portion formed integrally with the shaft portion, having a diameter larger than that of the shaft portion, and formed with rotor grooves arranged at intervals in a circumferential direction and extending in an axial direction; and a plurality of conductor bars penetrating the rotor slots and coupled to each other at both outer sides of the rotor core portion in the axial direction;

a stator having: a cylindrical stator core provided radially outside the rotor core portion; and a stator winding penetrating the inside of a plurality of stator slots extending in the axial direction, the plurality of stator slots being formed on the radially inner surface of the stator core at intervals in the circumferential direction; and

two bearings that support the block-shaped rotor on each of both sides of the axial shaft portion with the rotor core portion interposed therebetween,

the two walls of the rotor groove that face each other are inclined at a predetermined angle or more in the circumferential direction with respect to a plane that includes the rotation axis of the shaft portion.

2. The cage-type induction rotating electric machine according to claim 1, characterized in that the rotor slots are arranged at equal intervals from each other in the circumferential direction,

the stator slots are arranged at equal intervals from each other in the circumferential direction,

the number of rotor slots is equal to or greater than a predetermined ratio of 1 to the number of stator slots.

3. Cage-type induction rotating machine according to claim 2,

the predetermined ratio is 1.1 or more.

4. Cage-type induction rotating machine according to any one of claims 1 to 3,

in a cross section of the rotor slot, a radially innermost wall is formed in a curved shape.

5. Cage-type induction rotating machine according to any one of claims 1 to 4,

the outer end portions of the plurality of conductor bars in the radial direction are formed in the same cylindrical shape as the outer surface of the rotor core portion in the radial direction.

6. Cage-type induction rotating machine according to any one of claims 1 to 5,

the predetermined angle is 20 degrees or more.

7. A block rotor used in a cage-type induction rotating machine, comprising:

a shaft portion extending in an axial direction and rotatably supported;

a cylindrical rotor core portion formed integrally with the shaft portion, having a diameter larger than that of the shaft portion, and formed with rotor grooves arranged at intervals in a circumferential direction and extending in an axial direction; and

a plurality of conductor bars penetrating the rotor slots and coupled to each other at both outer sides of the rotor core portion in the axial direction;

the two walls of the rotor groove that face each other are inclined at a predetermined angle or more in the circumferential direction with respect to a plane that includes the rotation axis of the shaft portion.

8. A method for designing a cage-type induction rotating machine, comprising: a block-shaped rotor having a shaft portion and a rotor core portion formed integrally; and a stator disposed radially outward of the rotor core portion,

the method for designing a cage-type induction rotating machine is characterized by comprising:

a stator condition setting step of setting a size and a circumferential pitch of a plurality of stator slots penetrating in an axial direction, the plurality of stator slots being formed on a radially inner surface of the stator and arranged at intervals in a circumferential direction;

a rotor condition setting step of setting a size and a circumferential pitch of rotor slots penetrating in an axial direction, the rotor slots being formed on a radially outer surface of the rotor core portion and arranged at intervals in a circumferential direction, after the stator condition setting step;

an inclination angle setting step of setting an inclination angle of the rotor groove in the circumferential direction after the rotor condition setting step;

a stress calculation step of calculating a stress of the rotor core portion after the inclination angle setting step;

a temperature calculation step of calculating a temperature of the rotor core portion after the inclination angle setting step;

an angle range determination step of determining whether or not the rotor slot is ended in a study range of the inclination angle in the circumferential direction, and if it is determined that the rotor slot is not ended, performing the steps after the inclination angle setting step;

a pitch range determination step of, when it is determined in the angle range determination step that the rotor slot is ended within a study range of the inclination angle in the circumferential direction of the rotor slot, determining whether the rotor slot is ended within the study range of the pitch of the rotor slot, and when it is determined that the rotor slot is not ended, performing the steps after the rotor condition setting step; and

a determining step of determining the inclination angle and pitch of the rotor slots based on results of the stress calculating step and the temperature calculating step when it is determined in the pitch range determining step that the rotor slots have completed within a range of consideration of the pitch of the rotor slots.

Technical Field

The present invention relates to a cage-type induction rotating machine, a block rotor used in the cage-type induction rotating machine, and a method of designing the cage-type induction rotating machine.

Background

The induction rotating machine has a restriction that power factor adjustment or the like cannot be performed as in the case of a synchronous rotating machine, but has an advantage of a simple structure as compared with the synchronous rotating machine. Induction rotating electric machines generally include a wound-rotor type induction rotating electric machine and a cage type induction rotating electric machine. The cage-type induction rotating machine does not require electrical connection with the outside as in the case of the wound-rotor induction rotating machine, and is simpler in structure than the wound-rotor induction rotating machine. In particular, cage-type induction rotating machines are often used in combination with a power supply side because the power semiconductors have been developed to facilitate control of the machines.

In a cage-type induction rotating machine, a plurality of rotor slots are formed near the radial surface of a rotor core, the rotor slots being arranged at intervals in the circumferential direction and penetrating in the axial direction. The conductor bars pass through the respective rotor slots, and the conductor bars are electrically coupled to each other by a short-circuiting ring on the outside in the axial direction of the rotor core. The rotor grooves are formed in a direction from the front surface side of the rotor core toward the central axis of rotation, and the cross-sectional shape thereof may be, for example, a shape close to a rectangular shape (see patent document 1), a shape close to an egg-shaped shape (see patent document 2), or the like.

Alternatively, the conductor bars and the short-circuit rings may be integrally manufactured by casting, for example, aluminum (see patent document 3).

Disclosure of Invention

Technical problem to be solved by the invention

The rotor is generally configured by mounting a rotor shaft and a rotor core made of laminated plates on the radially outer side of the rotor shaft. In this case, since the laminated plates are electrically insulated from each other, no eddy current is generated in the axial direction. In the cage-type induction rotating electrical machine having the rotor core formed of the laminated plates, there is known a technique for suppressing heat generation in the conductor bars of the rotor to reduce the heat generation in the rotor (see patent document 4).

In a high-speed machine used in a region with a high rotational speed, a block-shaped magnetic pole rotor (block-shaped rotor) in which a rotor core and a rotor shaft are integrated with each other is sometimes used for the purpose of further securing mechanical strength. In such a case, since the centrifugal force acting on the conductor bars increases, it is necessary to reliably prevent the conductor bars from coming off radially outward. Since the direction of the centrifugal force coincides with the direction in which the grooves are formed, for example, a method of crimping the conductor bars to the rotor core is employed (see patent document 5).

The block rotor has a simpler structure and superior mechanical strength compared to a rotor having a laminated structure, but generates eddy current in the axial direction, and therefore has a larger loss compared to a rotor having a damaged laminated structure. As a result, there is a problem that the temperature of the surface of the rotor core rises.

Therefore, an object of the present invention is to reliably prevent conductor bars from coming off radially outward and to suppress an increase in the surface temperature of a rotor core portion of a block rotor in a cage-type induction rotating machine having the block rotor.

Means for solving the problems

In order to achieve the above object, a cage-type induction rotating machine according to the present invention includes: a block rotor having: a shaft portion extending in an axial direction and rotatably supported; a cylindrical rotor core portion formed integrally with the shaft portion, having a diameter larger than that of the shaft portion, and formed with rotor grooves arranged at intervals in a circumferential direction and extending in an axial direction; and a plurality of conductor bars penetrating the rotor slots and coupled to each other at both outer sides of the rotor core portion in the axial direction; a stator having: a cylindrical stator core provided radially outside the rotor core portion; and a stator winding penetrating the inside of a plurality of stator slots extending in the axial direction, the plurality of stator slots being formed on the radially inner surface of the stator core at intervals in the circumferential direction; and two bearings that support the block-shaped rotor on each of both sides of the shaft portion in the axial direction with the rotor core portion interposed therebetween, wherein two walls of the rotor groove that face each other are inclined at a predetermined angle or more in the circumferential direction with respect to a plane including the rotation axis of the shaft portion.

A block rotor according to the present invention is a block rotor used for a cage-type induction rotating machine, comprising: a shaft portion extending in an axial direction and rotatably supported; a cylindrical rotor core portion formed integrally with the shaft portion, having a diameter larger than that of the shaft portion, and formed with rotor grooves arranged at intervals in a circumferential direction and extending in an axial direction; and a plurality of conductor bars penetrating the rotor slot and coupled to each other at both outer sides of the rotor core portion in the axial direction; the two walls of the rotor groove that face each other are inclined at a predetermined angle or more in the circumferential direction with respect to a plane that includes the rotation axis of the shaft portion.

In addition, a method of designing a cage-type induction rotating machine according to the present invention includes: a block-shaped rotor having a shaft portion and a rotor core portion formed integrally; and a stator disposed radially outside the rotor core portion, the method for designing a cage-type induction rotating machine comprising: a stator condition setting step of setting a size and a circumferential pitch of a plurality of stator slots penetrating in an axial direction, the plurality of stator slots being formed on a radially inner surface of the stator and arranged at intervals in a circumferential direction; a rotor condition setting step of setting a size and a circumferential pitch of rotor slots penetrating in an axial direction, the rotor slots being formed on a radially outer surface of the rotor core portion and arranged at intervals in a circumferential direction, after the stator condition setting step; an inclination angle setting step of setting an inclination angle of the rotor groove in the circumferential direction after the rotor condition setting step; a stress calculation step of calculating a stress of the rotor core portion after the inclination angle setting step; a temperature calculation step of calculating a temperature of the rotor core portion after the inclination angle setting step; an angle range determination step of determining whether or not the rotor slot is ended in a study range of the inclination angle in the circumferential direction, and if it is determined that the rotor slot is not ended, performing the steps after the inclination angle setting step; a pitch range determination step of, when it is determined in the angle range determination step that the rotor slot is ended within a study range of the inclination angle in the circumferential direction of the rotor slot, determining whether the rotor slot is ended within the study range of the pitch of the rotor slot, and when it is determined that the rotor slot is not ended, performing the steps after the rotor condition setting step; and a determining step of determining the inclination angle and pitch of the rotor slots based on results of the stress calculating step and the temperature calculating step when it is determined in the pitch range determining step that the rotor slots have been completed within a range of consideration of the pitch of the rotor slots

Effects of the invention

According to the present invention, in a cage-type induction rotating machine having a block rotor, it is possible to reliably prevent conductor bars from coming off radially outward and to suppress an increase in the surface temperature of a rotor core portion of the block rotor.

Drawings

Fig. 1 is a vertical sectional view showing a structure of a cage-type induction rotating machine according to an embodiment.

Fig. 2 is a cross-sectional view showing a block rotor and a stator slot of the cage-type induction rotating machine according to the embodiment.

Fig. 3 is a flowchart showing steps of a method for designing a block rotor of a cage-type induction rotating machine according to an embodiment.

Fig. 4 is a graph showing a trial calculation example of a relationship between the number of rotor slots and the generated stress in the block rotor of the cage-type induction rotating machine according to the embodiment.

Fig. 5 is a graph showing a trial calculation example of the relationship between the number of rotor slots and the loss in the block rotor of the cage-type induction rotating machine according to the embodiment.

Fig. 6 is a first schematic partial cross-sectional view for explaining a relationship between stator slots and rotor slots of the cage-type induction rotating machine of the embodiment.

Fig. 7 is a second schematic partial cross-sectional view for explaining the relationship between the stator slots and the rotor slots of the cage-type induction rotating machine of the embodiment.

Fig. 8 is a third schematic partial cross-sectional view for explaining the relationship between the stator slots and the rotor slots of the cage-type induction rotating machine of the embodiment.

Fig. 9 is a graph showing a trial calculation example of the relationship between the number of rotor slots and the loss in the block rotor of the cage-type induction rotating machine according to the embodiment.

Fig. 10 is a partial cross-sectional view illustrating a rotor slot inclination angle of the block rotor according to the embodiment.

Fig. 11 is a cross-sectional view showing the block rotor and the stator slot when the rotor slot inclination angle of the block rotor of the embodiment is zero.

Fig. 12 is a schematic partial cross-sectional view illustrating an effect of a block rotor of the cage-type induction rotating machine of the embodiment.

Fig. 13 is a graph for explaining the effect of the block rotor of the cage-type induction rotating machine of the embodiment, and conceptually explaining the contents of the creation of the permission map and the determination of the rotor slot inclination angle and pitch in the method of designing the cage-type induction rotating machine.

Detailed Description

Hereinafter, a cage-type induction rotating machine, a block rotor, and a method of designing the cage-type induction rotating machine according to the present invention will be described with reference to the drawings. Here, the same or similar portions are given the same reference numerals, and overlapping description is omitted.

Fig. 1 is a vertical sectional view showing a structure of a cage-type induction rotating machine according to an embodiment.

Cage-type induction rotating electric machine 100 includes block rotor 10, stator 20, bearing 30, frame 40, and cooler 51.

The block rotor 10 is a block magnetic pole type rotor in which a rotor core and a rotor shaft are integrated for the purpose of further securing mechanical strength, and includes an integrated rotor 11, a plurality of conductor bars 16, and two short-circuiting rings 17.

The integrated rotor 11 is a rotationally symmetric integrated body, and has a shape in which cylindrical shapes having different diameters are combined in the rotation axis direction (hereinafter, axial direction). The rotor core portion 13 is formed in a cylindrical shape having a large diameter near the center in the axial direction. Shaft portions 12 having a smaller diameter than the rotor core portion 13 are formed on both sides in the axial direction with the rotor core portion 13 interposed therebetween. The shaft portions 12 on both sides in the axial direction are rotatably supported by bearings 30. An inner fan 18 is provided in each shaft portion 12 at a portion between the rotor core portion 13 and the bearing 30.

As described later, the plurality of conductor bars 16 extend in the axial direction through the vicinity of the radial surface of the rotor core portion 13. The conductor bars 16 protrude by the same length on both outer sides in the axial direction of the rotor core portion 13. On each of the axially outer sides, the ends of the plurality of conductor bars 16 are electrically and mechanically coupled to each other by being electrically and mechanically coupled to an annular short ring 17. The conductor bars 16 and the short-circuit rings 17 are made of a material having a higher electrical conductivity than the rotor core portion 13. For example, the rotor core portion 13 is made of steel, low alloy steel, or the like, while the conductor bars 16 and the short-circuit rings 17 are made of copper, aluminum, or the like.

The stator 20 includes a stator core 21 and a plurality of stator windings 24. The stator core 21 is disposed radially outward of the rotor core portion 13 of the block rotor 10 with an annular gap 25 therebetween. The stator core 21 is cylindrical, and the stator winding 24 penetrates the vicinity of the inner surface of the stator core 21.

The frame 40 houses the stator 20 and the rotor core portion 13. The frame 40 is provided with bearing brackets 35 at both axial ends thereof. The bearing brackets 35 support the bearings 30 at rest, respectively.

A cooler 51 is provided above the frame 40 and is housed in a cooler cover 52. The cooler cover 52 forms an enclosed space 61 together with the frame 40 and the two bearing brackets 35. The closed space 61 is filled with cooling gas such as air, and the cooling gas is circulated in the closed space 61 by the inner fan 18. The space in the cooler cover 52 and the space in the frame 40 constituting the closed space 61 communicate with each other via a cooler inlet opening 62 formed above the stator 20 and a cooler outlet opening 63 formed above each inner fan 18.

Fig. 2 is a cross-sectional view showing a block rotor and a stator slot of the cage-type induction rotating machine according to the embodiment.

A plurality of groove-like rotor grooves 14 are formed in the surface of the rotor core portion 13, and the plurality of rotor grooves 14 are arranged at intervals in the circumferential direction, extend in the axial direction, and have a width d. The conductor bars 16 pass through each rotor slot 14. Each rotor groove 14 has an outer wall 14a and an inner wall 14b extending in the axial direction, facing each other and parallel to each other, and a radially innermost wall 14 c. The innermost wall 14c is formed in a curved shape in the cross section of the rotor slot 14. In the radial direction, each rotor groove 14 is formed to a depth up to the inscribed circle 14 d.

The conductor bars 16 and the rotor slots 14 have respective cross-sectional shapes and sizes substantially equal to each other. The conductor bars 16 are flat plates that are long in the axial direction. The conductor bars 16 can be fitted into the rotor slots 14 from the outside in the radial direction of the rotor slots 14. In order to prevent the conductor bars 16 from falling off the rotor slots 14, for example, the portions of the conductor bars 16 facing the outer side wall 14a, the inner side wall 14b, and the innermost wall 14c may be wound with silver solder foil, inserted into the rotor slots 14, and melted. Alternatively, a method of inserting the conductor bar 16 into the rotor slot 14 and then performing TIG welding from the outside or crimping the conductor bar 16 to the rotor slot 14 may be employed.

The radially outer end of each of the plurality of conductor bars 16 is formed to be a part of a cylinder similar to the cylinder formed on the radially outer surface of the rotor core portion 13. Further, for example, the radially outer end portion of the conductor bar may be perpendicular to both surfaces of the conductor bar, and the radially outer side may be partially retreated radially inward from the cylindrical shape.

Further, the case where the conductor bars 16 can be fitted into the rotor slots 14 from the outside in the radial direction of the rotor slots 14 has been described as an example, but they may be inserted from the axial end of the rotor core portion 13. In this case, the conductor bars 16 may be formed not in a flat plate shape but with a maximum thickness or a minimum thickness in the middle in the width direction to overcome the centrifugal force.

The rotor slots 14 are not formed in the radial direction from the center axis, but have an inclination in the circumferential direction. The details are illustrated in fig. 10. As a result of the formation of the rotor slots 14, the rotor teeth 15 are formed in the same number as the rotor slots 14, and are arranged at intervals in the circumferential direction.

A plurality of groove-shaped stator slots 22 are formed on the radially inner surface of the stator core 21 disposed radially outward with the gap 25 interposed therebetween, and are disposed at intervals in the circumferential direction and extend in the axial direction. As a result, the same number of stator teeth 23 as the stator slots 22 are formed, which are arranged at intervals in the circumferential direction. The direction of the stator teeth 23 is formed such that the center plane of the mutually opposing side walls of the stator slot 22 passes through the center axis of the block rotor 10. Stator winding conductors 24a extend through each stator slot 22, the stator winding conductors 24a forming the stator windings 24.

Here, the inclination angle Φ and the pitch of the rotor slots 14 in the circumferential direction and the pitch of the stator slots 22 will be described.

The inclination angle Φ in the circumferential direction of the rotor groove 14 is an angle formed by a line extending from the rotation center axis 11a of the rotor core portion 13 to the intersection PP1 of the center line in the width direction of the rotor groove 14 and the circumscribed circle of the block rotor 10 and the center line in the width direction of the rotor groove 14 in the cross section perpendicular to the axial direction shown in fig. 2. Conventionally, this angle Φ is zero, but in the present embodiment, is larger than 0, i.e., is inclined with respect to a line passing through the center.

There are several ways of expressing the pitch of the rotor slots 14. That is, in the cross section perpendicular to the axial direction shown in fig. 2, the circumferential angle interval Δ θ r between the point PP1 and the point PP2 of the block rotor 10 can be expressed. Alternatively, the interval Δ Pr between the point PP1 and the point PP2 may be used. Although not shown, the distance may be set to the circumferential distance between the point PP1 and the point PP2 on the circumscribed circle of the rotor core portion 13. When the diameter of the rotor core portion 13, that is, the diameter of the circumscribed circle of the rotor core portion 13 is determined, the circumferential angle interval Δ θ r representing the pitch of the rotor grooves 14 corresponds to the interval Δ Pr one-to-one, and the number of rotor grooves also corresponds to one-to-one.

The pitch of the stator slots 22 can be expressed by the circumferential angle interval Δ θ s or the interval Δ Ps as shown in fig. 2. When the size of the stator core 21 is determined, the circumferential angle interval Δ θ s corresponds to the interval Δ Ps one-to-one, and the number of stator slots also corresponds to one-to-one.

Hereinafter, the pitch of the rotor slots 14 or the pitch of the stator slots 22 refers to a pitch expressed by either one of them.

Fig. 3 is a flowchart showing steps of a method for designing a block rotor of a cage-type induction rotating machine according to an embodiment. That is, the steps of the design method for evaluating the optimum range of the inclination angle Φ of the rotor slots 14 in the circumferential direction (hereinafter, the rotor slot inclination angle Φ) are shown.

First, conditions of the stator slots 22 such as the size of the stator slots 22 and the circumferential pitch are set (step S01). In addition, the size of the stator winding conductor 24a penetrating the stator slot 22 is also set together with the setting of the condition of the stator slot 22.

Next, conditions of the rotor grooves 14, such as the size of the rotor grooves 14 and the pitch in the circumferential direction, are set (step S02).

Next, the rotor slot inclination angle Φ is set (step S03). The size and shape of the conductor bar 16 penetrating the rotor slot 14 are also set together with the setting of the condition of the rotor slot 14.

In addition to the conditions relating to the rotor slots 14 and the stator slots 22, the conditions such as the dimensions of the block rotor 10, the stator 20, and the air gap 25 are set in advance.

As a result of the above, since the conditions relating to the rotor slots 14 and the stator slots 22 are determined, the loss in the rotor core portion 13 of the block rotor 10 is calculated next (step S04). Next, the temperature distribution of the rotor core portion 13 is calculated based on the calculated loss (step S05).

In addition, the stress distribution of the rotor core portion 13 is calculated in parallel with the temperature calculation in steps S04 and S05 (step S06).

Next, it is determined whether or not the steps up to step S06 have ended over the range to be investigated regarding the rotor slot inclination angle Φ (step S07). Here, if a range to be studied about the rotor groove inclination angle Φ is a range from Φ smin to Φ smax, Φ smin is an angle larger than 0 degree and Φ smax is an angle smaller than 90 degrees. Specifically, for example, Φ smin may be set to 10 degrees, Φ smax may be set to 80 degrees, or the range may be set to a somewhat wider range, or the range may be further narrowed.

If it is determined that the steps up to step S06 have not ended over the range of the rotor slot inclination angle Φ to be examined (no at step S07), the process returns to step S03, and the rotor slot inclination angle Φ is changed and the process proceeds to step S06.

If it is determined that the sequence up to step S06 has ended over the range to be investigated regarding the rotor slot inclination angle Φ (step S07: yes), it is next determined whether or not the sequence up to step S06 has ended over the range to be investigated regarding the pitch of the rotor slots 14 (step S08). If it is determined that the steps up to step S06 have not ended over the range to be examined regarding the pitch of the rotor slots 14 (no in step S08), the process returns to step S02, and the pitch of the rotor slots 14 is changed and the process proceeds to step S06.

If it is determined that the steps up to step S06 have ended over the range to be examined regarding the pitch of the rotor slots 14 (step S08: yes), the process proceeds to next step S10.

Further, until the stage of step S10, an evaluation function is determined (step S09). The evaluation function is, for example, an evaluation function PI (n) as shown in the following expression (2) or (3) for minimizing the total of the generated stress and the loss with respect to the number n of rotor slots, an evaluation function PI (Φ/n0) as shown in the following expression (4) for minimizing the total of the generated stress and the loss, or the like.

Next, the number n of rotor slots of the rotor slots 14 and the rotor slot inclination angles Φ and are determined based on the evaluation function set in step S09 (step S10).

The steps of the block rotor design method shown in fig. 3 have been described briefly above, and the steps from step S02 to step S08 are measurements (surfey) in the predetermined study range of the rotor groove inclination angle Φ and the study range of the pitch of the rotor grooves 14 or the corresponding number n of rotor grooves. Actually, the determination of the number n of rotor slots of the rotor slots 14 and the rotor slot inclination angle Φ is performed in step S09 and step S10 based on the metering results. The contents of this stage will be described below.

Fig. 4 is a graph showing a trial calculation example of a relationship between the number of rotor slots and the generated stress in the block rotor of the cage-type induction rotating machine according to the embodiment. The horizontal axis represents the number n of rotor slots relative to the reference number n₀The ratio of (a) to (b). The vertical axis represents the number n of rotor slots based on the reference₀The ratio (relative value) of the generated stress with respect to the generated stress in (2).

The curve shown by the broken line indicates a case where the groove width d of the rotor groove 14 is changed in inverse proportion to the number of grooves of the rotor groove 14. The curve indicated by the two-dot chain line indicates a case where the groove width d of the rotor groove 14 is fixed. Here, the generated stress indicates the stress at the root of the rotor tooth 15, which is the largest in the stress distribution.

As shown in fig. 4, when the number of slots of the rotor slot 14 is increased, even if the slot width d is decreased in accordance with the increase in the number of slots, the degree of the increase is relaxed, but the stress increases.

Fig. 5 is a graph showing a trial calculation example of the relationship between the number of rotor slots and the loss in the block rotor of the cage-type induction rotating machine according to the embodiment. The horizontal axis represents the number n of rotor slots relative to the reference number n₀The ratio of (a) to (b). The vertical axis represents the number n of rotor slots based on the reference₀The loss at the time of next is a ratio (relative value) of the loss of the reference.

As shown in fig. 5, as the number of rotor slots 14 increases, the loss decreases. In this regard, fig. 6 to 8 are referred to below for supplement.

Fig. 6 is a first schematic partial cross-sectional view for explaining a relationship between stator slots and rotor slots of the cage-type induction rotating machine of the embodiment. Fig. 7 is a second conceptual partial cross-sectional view. Fig. 8 is a third conceptual partial cross-sectional view. In either case, the stator winding conductors 24a (fig. 2) are omitted from illustration. In each figure, the curve shown by the broken line conceptually shows a state at a certain moment of the distribution of the magnetic flux generated by the stator winding 24 (fig. 1).

Now, the number of rotor slots 14 is N, and the number of stator slots 22 is N. Fig. 6 shows a case where the number N of rotor slots is equal to the number N of stator slots. The circumferential intensity distribution (circumferential magnetic flux intensity distribution) of the magnetic flux formed by the current flowing through the stator winding 24 has a phase pitch, i.e., a period, corresponding to the distribution of the positions of the stator slots 22. Therefore, for example, when a circumferential magnetic flux intensity distribution shown by a dotted line in fig. 6 is generated, the magnetic flux does not penetrate the conductor bars 16.

When the number N of rotor slots is smaller than the number N of stator slots, the time during which the magnetic flux does not penetrate the conductor bars 16 is further increased. Thus, the magnetic flux formed by the current flowing through the stator winding 24 does not penetrate into the conductor bars 16 and becomes leakage magnetic flux, which causes a reduction in the efficiency of the induction motor.

The second conceptual diagram of fig. 7 shows a case where the number N of rotor slots is larger than the number N of stator slots. In this case, the pitch of the rows of the rotor slots 14 is different from the period of the intensity distribution of the circumferential magnetic flux generated by the current flowing through the stator winding 24, that is, the pitch of the phases. Therefore, the magnetic flux is surely permeated into the conductor bars 16. In this case, a part of the magnetic flux must penetrate the directional conductor strip 16. In addition, the portion that does not penetrate the conductor bars becomes leakage magnetic flux.

The third conceptual diagram of fig. 8 shows a case where the number N of rotor slots is further increased to 2 times the number N of stator slots. In this case, the magnetic flux always penetrates the conductor bars 16 in any phase, and the amount of leakage magnetic flux is smaller than in the case of the first and second conceptual diagrams, and the magnetic loss is minimized.

In this way, it is considered that when the number N of rotor slots 14 is increased from the number equal to the number N of stator slots 22 by a factor of 2, the magnetic flux generated by the stator winding 24 (fig. 1) and the conductor bars 16 of the block rotor 10 are strongly coupled. This becomes a main cause of reducing loss.

From the above, regarding the loss, it is preferable that the condition of the following expression (1) is satisfied when the number N of rotor slots is larger than the number N of stator slots.

n/N≥1.1···(1)

Fig. 9 is a graph showing a trial calculation example of the relationship between the number of rotor slots and the loss in the block rotor of the cage-type induction rotating machine according to the embodiment. That is, the contents of fig. 4 and the contents of fig. 5 are summarized as one diagram. The horizontal axis represents the number n of rotor slots relative to the reference number n₀The ratio of (a) to (b). The vertical axis represents the number n of rotor slots based on the reference₀Ratio (relative value) of generated stress based on generated stress at the lower part, and the number n of rotor slots based on the reference₀The loss of (c) is a ratio (relative value) of the loss of the reference.

The curve shown by the solid line indicates loss, the curve shown by the broken line and the two-dot chain line indicates generation of stress, the groove width is fixed in the case of the two-dot chain line, and the evaluation result under the condition that the groove width is reduced in the case of the broken line.

The generated stress tends to increase with an increase in the number of rotor slots 14, while the loss tends to decrease. That is, the generated stress and the loss show characteristics of opposing each other with respect to an increase in the number of the rotor slots 14.

The generation of stress and loss are characteristic values different from each other, but are main causes of disadvantages, which are consistent. Therefore, these two disadvantages are converted to common evaluation criteria, i.e., common evaluation criteria, and the disadvantages are minimized as a whole.

Now, the stress generated when the number of rotor slots is n0 is S₀Let the loss be L₀. Here, n is₀Is arbitrary.

Now, the stress generated when the number of rotor slots is n is s (n), and the loss is l (n). In this case, for example, by minimizing the first evaluation function pin (n) shown by the following expression (2) with respect to n, the number of rotor slots that minimizes the occurrence of stress and loss as a whole can be obtained.

PIn(n)＝[S(n)/S₀]+p·[L(n)/L₀]…(2)

Alternatively, as the first evaluation function pi (n), a function expressed by the following formula (3) may be used.

PIn(n)＝[S(n)/S₀]·[L(n)/L₀]^p…(3)

S in the formulae (2) and (3)₀And L₀Is an arbitrary reference value. The constant p is a constant for taking into account the mutual weighting between the disadvantage due to the occurrence of the stress s (n) and the disadvantage due to the loss l (n), and is set in consideration of the purpose of the target rotating electric machine, the design margin, and the like.

In this way, the first step of evaluating the number n of rotor slots is to calculate a specific value at which the above-described expression (2) or expression (3) is the smallest. In this case, when the procedure of determining the rotor slot inclination angle Φ in the next second step is considered, the number of rotor slots does not necessarily match the optimum condition as the combination of the number of rotor slots n and the rotor slot inclination angle Φ. Therefore, the number n of rotor slots is selected to have a sufficient width.

Fig. 10 is a partial cross-sectional view illustrating a rotor slot inclination angle of the block rotor according to the embodiment. Now, a virtual surface 14s between the outer wall 14a and the inner wall 14b facing each other and parallel to each other in the same rotor slot 14 is considered. The radial surface of the rotor core portion 13 is a curved surface Sf. The intersection of the curved surface Sf and the virtual surface 14s is defined as an intersection L0. Further, a plane passing through the rotation center axis 11a and the intersection line L0 is defined as a plane P.

As a result, the intersection line L0 passes through two planes, i.e., the virtual plane 14s and the plane P. The circumferential intersection angle formed by the two planes is set as a rotor slot inclination angle Φ. Wherein the rotor slot inclination angle phi is more than 0 degree and less than 90 degrees. An angle formed by a plane P1 and a plane P2 that pass through an intersection line L1 and an intersection line L2 that are adjacent to each other is defined as a pitch angle Δ θ r. Wherein the pitching angle delta theta r is more than 0 degree and less than 90 degrees.

Fig. 11 is a cross-sectional view showing the block rotor and the stator slot when the rotor slot inclination angle of the block rotor of the embodiment is zero. That is, the orientation of conventional rotor groove 74 is shown. The surfaces of the centers of the two opposing walls 74a of the rotor groove 74 parallel to each other are the surfaces passing through the rotation center axis 11a, and the innermost portion 74c is formed closest to the rotation center axis 11a, i.e., deepest, as compared with the present embodiment. The virtual surface 14s shown in fig. 10 is the same plane as the plane P, and in this case, the rotor slot inclination angle Φ defined in the same manner as in fig. 10 is 0 degree.

As described above, in the block rotor 10 of the cage-type induction rotating machine 100 of the present embodiment, the rotor grooves 14 formed on the surface of the rotor core portion 13 of the block rotor 10 are inclined in the circumferential direction. In addition, the ratio of the number of rotor slots 14 to the number of stator slots 22 is greater than 1.1.

Fig. 12 is a conceptual partial cross-sectional view illustrating an effect of the block rotor of the cage-type induction rotating machine according to the embodiment. Two on the left side of the figure are the rotor slots 14 and the conductor bars 16 of the rotor core portion 13 of the present embodiment. On the right side, for comparison, the conductor bars having the same cross-sectional area as the conventional rotor slots and the conductor bars of the present embodiment are shown by broken lines.

The radius of the inscribed circle 14d of the rotor groove 14 in the present embodiment is larger than the radius of the inscribed circle Si0 of the conventional rotor groove. That is, the radial width Δ R1 of the rotor groove 14 of the present embodiment is smaller than the radial width Δ R0 of the conventional rotor groove. Therefore, the entire position of each conductor bar 16 (e.g., the center position) is close to the surface of the rotor core portion 13, and the interval between the entire position (e.g., the center position) in each conductor bar 16 and the stator winding 24 is relatively short. Δ R1 is substantially Δ R0. cos Φ.

In general, core loss occurs in the rotor core portion 13 having relatively lower conductivity than the conductor bars 16, and since induced current flows particularly on the surface of the rotor core portion 13, the temperature of the surface of the rotor core portion 13 tends to increase.

The relative shortening of the interval between the entire position of the conductor bars 16 and the stator winding 24 increases the coupling force by the magnetic flux passing through the stator core 21 and the conductor bars 16, resulting in an improvement in efficiency. As a result, the loss is reduced. Therefore, the increase in the surface temperature Ts of the rotor core portion 13 in the present embodiment is suppressed to be lower than that in the related art. The larger the rotor slot inclination angle Φ, the greater the effect.

As a standard for securing this effect, it is necessary to include the stator winding 24 for evaluation, but it is considered that the ratio of the width in the radial direction of the rotor slot 14 needs to be reduced by at least about 5% to 10%, for example. In this case, cos Φ has a value of 0.9 to 0.95, that is, Φ is 18 degrees to 26 degrees. Therefore, it is considered that at least the rotor slot inclination angle Φ needs to be at least about 20 degrees.

In addition, if the reduction is about 20% to 30%, the effect is considered to be sufficient. In this case, the value of cos Φ is 0.7 to 0.8, i.e., Φ is 37 to 46 degrees, according to Δ R1 ═ Δ R0cos Φ. Therefore, the rotor slot inclination angle Φ is preferably about 40 to 45 degrees.

In fig. 12, a centrifugal force F acting at the center of gravity M in the cross section of the conductor bar 16 is decomposed into a component Fh in a direction in which the conductor bar 16 is to be pulled out along the rotor slot 14 and a component Fw in a direction perpendicular thereto and acting on the outer sidewall 14a of the rotor slot 14.

The value of the component force Fh is Fcos Φ, which is smaller than the value of the centrifugal force F. Therefore, when the same degree of flying-out prevention measures as in the conventional art are taken, the amount of (F-Fcos Φ) is a margin for flying-out prevention. Further, although a large-scale apparatus is conventionally required for, for example, pressure bonding, etc., a measure for preventing flying out, such as brazing, etc., using an apparatus that does not need to be so large may be required, and a margin for preventing flying out may be secured to the same extent as in the related art.

On the other hand, the component force Fw in the direction in which the outer wall 14a acts has a value Fsin Φ, and acts on the rotor teeth 15 in the circumferential direction to bend the rotor teeth 15 in such a direction as to extend in the radial direction. In this case, the stress distribution of the rotor teeth 15 produces a maximum value Smax at the root portions 15c of the rotor teeth 15. Therefore, the maximum value Smax is the rotor slot inclination angle in a range in which the allowable stress is sufficiently small.

As described above, in the block rotor 10 of the present embodiment, by inclining the rotor grooves 14 in the circumferential direction, it is possible to suppress the loss L which causes the surface temperature of the rotor core portion 13 to increase while alleviating the condition for preventing the conductor bars 16 from falling off from the rotor grooves 14.

As described in equation (3), the number of rotor slots 14 is set to be larger than 1.1 times the number of stator slots 22, thereby further improving the efficiency. Therefore, the increase in the surface temperature Ts of the rotor core portion 13 can be further suppressed.

Fig. 13 is a graph for explaining the effect of the block rotor of the cage-type induction rotating machine of the embodiment, and conceptually explaining the contents of the creation of the permission map and the determination of the rotor slot inclination angle and pitch in the method of designing the cage-type induction rotating machine. The horizontal axis is the rotor slot inclination angle Φ. The vertical axis represents the loss L (Φ, n) shown by the curve A0₀) Evaluation value of (2), and stress generation S (Φ, n) shown by the curve B0₀) And an unfavorable evaluation function PI phi (phi, n) shown by a curve C0 obtained by synthesizing the above functions₀) The function value of (1).

Generating stress S (phi, n)₀) And loss L (phi, n)₀) Is relative to the number n of rotor slots₀The value of the rotor slot inclination angle Φ in the case of (1).

Adverse evaluation function PI phi (phi, n)₀) Represented by the following expression (4).

PIΦ(Φ，n₀)＝g[S(Φ，n₀)，L(Φ，n₀)]…(4)

Here, n is₀The value in the range of the number n of rotor grooves obtained in the first step, that is, the step of minimizing the number n of rotor grooves, such as the formula (2) or the formula (3), is treated as a parameter. That is, in the second step, that is, the step of minimizing the unfavorable evaluation function for the rotor slot inclination angle Φ, the processing is performed as a constant value. As a result, the number n of slots per rotor₀To obtain the unfavorable evaluation function PI phi (phi, n)₀) Minimum (number of rotor slots n)₀) And (rotor slot inclination angle Φ). In these combinations, the unfavorable evaluation function PI Φ (Φ, n)₀) The value of (c) is a combination of (the number of rotor slots n) and (the rotor slot inclination angle Φ) to be finally determined.

As PI Φ (Φ, n)₀) The following formula (5) is used.

PIΦ(Φ，n₀)＝[S(Φ，n₀)/S₀]+q·[L(Φ，n₀)/L₀]

…(5)

As the evaluation function pi (n), an evaluation function represented by the following formula (6) may be used.

PIΦ(Φ，n₀)＝[S(Φ，n₀)/S₀]·[L(Φ，n₀)/L₀)]^q

…(6)

S₀、L₀Is an arbitrary reference value. The constant q is a constant for taking into account the mutual weighting between the disadvantage due to the occurrence of the stress s (n) and the disadvantage due to the loss l (n), as in the case of p in the first step, and is set in consideration of the purpose of the target rotating electric machine, the design margin, and the like.

In addition, the above formulas (2) and (3) in the first step and the formulas (5) and (6) in the second step are examples, and are not limited thereto. That is, if there is an index influenced by the inclination angle Φ of the rotor slot 14, it can be added to the variables of these equations. In addition, when the influence is negligible, the influence may be excluded from the variables of the formula (1). In addition, functional shapes other than the above-described forms may be used.

As shown in FIG. 13, the larger the rotor slot inclination angle Φ is, the loss L (Φ, n)₀) The more reduced. On the other hand, the larger the rotor groove inclination angle Φ is, the larger the force acting on the outer side wall 14a to cause the rotor teeth 15 to bend in the circumferential direction is, and therefore, the larger the rotor groove inclination angle Φ is, the stress S (Φ, n) is generated₀) The larger. PI Φ (Φ, n)₀) As shown by the curve C0, the characteristic of the rotor groove inclination angle Φ increasing with an increase is that the inclination angle Φ increases after decreasing, and has a minimum value.

In addition, for the loss L (phi, n)₀) If the rotor slot inclination angle Φ at this time is Φ 0min, the range of Φ > Φ 0min and the rotor slot inclination angle Φ is limited under the condition of the limit value HL or less. Here, the limit value HL is, for example, the maximum temperature obtained by subtracting a predetermined margin from the upper limit of the temperature range in which the rotor core portion 13 can continue to operateThe loss L.

In addition, stress S (phi, n) is generated₀) If a condition equal to or less than the limit value HS is applied and the rotor slot inclination angle phi at this time is set to phi 0max, the range of phi < phi 0max and the rotor slot inclination angle phi is limited. Here, the limit value HS is, for example, a value obtained by subtracting a predetermined margin from an allowable stress of the material of the rotor core portion 13.

As shown by a solid line C0 in the example of fig. 13, when the rotor slot inclination angle Φ satisfying the condition of Φ 0min < Φ 0max has a minimum value, the rotor slot inclination angle Φ 0 that provides the minimum value is determined. The predetermined angular width Δ Φ is observed here, and the range from (Φ 0- Δ Φ) to (Φ 0+ Δ Φ) is set as the optimum range. Here, the angular width Δ Φ may be set to a value sufficiently larger than the accuracy in manufacturing the cage-type induction rotating electric machine 100 including the formation of the rotor slots 14, for example, to a value of about 5 degrees to 10 degrees.

As described above, in the block rotor 10 of the present embodiment, the rotor slots 14 are inclined in the circumferential direction, whereby the increase in the surface temperature Ts of the rotor core portion 13 can be suppressed while alleviating the condition for preventing the conductor bars 16 from falling off from the rotor slots 14, and the number of the rotor slots 14 is set to be larger than 1.1 times the number of the stator slots 22, thereby improving the efficiency. Therefore, the increase in the surface temperature Ts of the rotor core portion 13 can be further suppressed.

In addition, the stress S (phi, n) can be generated based on₀) And loss L (phi, n)₀) The number n of rotor slots 14 and the inclination angle Φ of the rotor slots 14 are set to optimum values.

In this way, in the cage-type induction rotating electric machine 100 having the block rotor 10, the conductor bars 16 can be reliably prevented from coming off radially outward, and an increase in the surface temperature Ts of the rotor core portion 13 can be suppressed.

[ other embodiments ]

The embodiments of the present invention have been described above, but the embodiments are provided as examples and are not intended to limit the scope of the invention. For example, in the embodiment, the case where the cooling device is fully closed is described as an example, but the present invention can be applied to a case other than the fully closed type, and can also be applied to a case where the cooling device is not provided.

The embodiments may be implemented in other various manners, and various omissions, substitutions, and changes may be made without departing from the spirit of the invention. The embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Description of the reference numerals

10 … block rotor, 11 … integral rotor, 11a … rotation center shaft, 12 … shaft, 13 … rotor core part, 14 … rotor slot, 14a … outer side wall, 14b … inner side wall, 14c … innermost wall, 14d … inscribed circle, 14s virtual plane, 15 … rotor tooth, 15c … root, 16 … conductor bar, 17 … short circuit ring, 18 … inner fan, 20 … stator, 21 … stator core, 22 … stator slot, 23 … stator tooth, 24 … stator winding, 24a … stator winding conductor, 25 … air gap, 30 … bearing, 35 … bearing bracket, 40 … frame, 51 … cooler, 52 … cooler cover, 61 … enclosed space, 62 … cooler inlet opening, 63 … cooler outlet opening, 74 … rotor slot, 74a … wall, 3674 a 3674 c … innermost part, 36100 type rotary induction motor.