WO2021192223A1

WO2021192223A1 - Solid rotor, squirrel cage induction rotating electric machine, and method for designing squirrel cage induction rotating electric machine

Info

Publication number: WO2021192223A1
Application number: PCT/JP2020/014028
Authority: WO
Inventors: 雄一坪井; 米谷　晴之
Original assignee: 東芝三菱電機産業システム株式会社; 三菱電機株式会社
Priority date: 2020-03-27
Filing date: 2020-03-27
Publication date: 2021-09-30
Also published as: JPWO2021192223A1; JP7168680B2

Abstract

This solid rotor (10) used in a squirrel cage induction rotating electric machine includes: a shaft part which extends in the axial direction and is rotatably supported; a columnar rotor core part (13) which is integrally formed coaxially with the shaft part and has a greater diameter than the shaft part, and in which are formed rotor slots (14) that are disposed with gaps therebetween in the circumferential direction and extend in the axial direction; and a plurality of conductor bars (16) which penetrate through the inside of the rotor slots (14) and are coupled to each other on both outer sides in the axial direction of the rotor core part (13). The two mutually opposing walls of each of the rotor slots (14) incline by at least a predetermined angle in the circumferential direction with respect to a plane that includes the axis of rotation of the shaft part. When viewed outward in the radial direction from the axis of rotation of the shaft part, regions where a portion of a plurality of conductor bars (16) among the plurality of conductor bars (16) are present and regions where the same is not present are alternately disposed in the circumferential direction.

Description

How to design massive rotors, squirrel-cage induction machines, and squirrel-cage induction machines

The present invention relates to a massive rotor, a squirrel-cage induction rotary electric machine having the lump rotor, and a method for designing a squirrel-cage induction rotary electric machine.

The induction rotary electric machine has restrictions such as not being able to adjust the power factor like the synchronous rotary electric machine, but has the advantage of having a simpler structure than the synchronous rotary electric machine. The induction rotary electric machine generally includes a winding type induction rotary electric machine and a cage type induction rotary electric machine. The cage-type induction rotary electric machine does not require an electrical connection with the outside like the winding-type induction rotary electric machine, and has a simpler structure than the winding-type induction rotary electric machine. In particular, for squirrel-cage induction rotary electric machines, control on the power supply side has become easier due to the development of semiconductors for electric power, so a method combined with this has come to be widely used.

In a squirrel-cage induction rotary electric machine, a plurality of rotor slots are formed in the vicinity of the radial surface of the rotor core, which are arranged at intervals in the circumferential direction and penetrate in the axial direction. A conductor bar penetrates each rotor slot, and the conductor bars are electrically connected to each other by a short-circuit ring on the axially outer side of the rotor core. The rotor slot is formed in the direction from the surface side of the rotor core toward the rotation axis of rotation, and its cross-sectional shape is, for example, a shape close to a rectangle (see Patent Document 1) or a shape close to an oval shape. (See Patent Document 2).

Alternatively, there is a case where the conductor bar and the short-circuit ring are integrally manufactured by casting, such as made of aluminum (see Patent Document 3).

Japanese Unexamined Patent Publication No. 2016-220404 Japanese Patent No. 3752781 Japanese Unexamined Patent Publication No. 2014-195374 Japanese Patent No. 5557685 U.S. Pat. No. 6,933,647

The rotor is generally configured by attaching a rotor shaft and a rotor core composed of laminated plates to the outside in the radial direction 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 a cage-type induction rotary electric machine having a rotor core made of a laminated plate as described above, a technique for reducing heat generation in the rotor by suppressing heat generation in the conductor bar of the rotor is known (patented). Reference 4).

In a high-speed machine used in a high rotation speed region, when a massive magnetic pole type rotor (lump rotor) in which a rotor core is integrated with a rotor shaft is adopted for the purpose of ensuring more mechanical strength. There is. In such a case, the centrifugal force acting on the conductor bar increases, so it is necessary to ensure that the conductor bar is prevented from coming off in the radial direction. Since the direction of the centrifugal force coincides with the direction in which the slot is formed, for example, a method such as pressing the conductor bar against the rotor core is adopted (see Patent Document 5).

The massive rotor has a simpler structure than the laminated rotor and has excellent mechanical strength, but it also generates an eddy current in the axial direction, so the loss is larger than that of the laminated rotor. Become. 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 suppress an increase in the surface temperature of the rotor core portion of the massive rotor while reducing the cost increase in the cage-shaped induction rotary electric machine having the massive rotor.

In order to achieve the above object, the massive rotor according to the present invention is a massive rotor used in a cage-shaped induction rotary electric machine, and includes a shaft portion extending in the axial direction and rotatably supported, and the shaft portion. A columnar rotor core portion formed coaxially integrally, having a diameter larger than that of the shaft portion, arranged at intervals in the circumferential direction, and extending in the axial direction, and the rotation. It has a plurality of conductor bars penetrating the inside of the child slot and connecting to each other on both outer sides of the rotor core portion in the axial direction, and the two walls of the rotor slot facing each other are the shaft portion. It is tilted by a predetermined angle or more in the circumferential direction with respect to the plane including the rotation axis of And non-existent regions are arranged alternately in the circumferential direction.

Further, the cage-shaped induction rotary electric machine according to the present invention includes the above-mentioned massive rotor, a cylindrical stator core provided on the radial outer side of the rotor core portion, and a radial inner side of the stator core. A stator having a stator winding formed on the surface at intervals in the circumferential direction and penetrating the inside of a plurality of stator slots extending in the axial direction, and a stator in the axial direction with the rotor core portion interposed therebetween. It is characterized by including two bearings that support the massive rotor on both sides of the shaft portion.

Further, the method for designing a cage-shaped induction rotary electric machine according to the present invention is a method of designing a massive rotor having a shaft portion and a rotor core portion, and fixing provided outside the rotor core portion in the radial direction. A method of designing a cage-type induction rotary electric machine including a child, which is a method of designing a plurality of stator slots formed on the radial inner surface of the stator, arranged at intervals in the circumferential direction, and penetrating in the axial direction. After the stator condition setting step for setting the dimensions and the pitch in the circumferential direction and the stator condition setting step, they are formed on the radial outer surface of the rotor core portion and arranged at intervals in the circumferential direction. A dense rotor condition setting step for obtaining a dense rotor by setting the dimensions of a rotor slot penetrating in the axial direction, a pitch in the circumferential direction, and a tilt angle in the circumferential direction, and the rotor of the dense rotor. Regarding the slots, the thinning step of forming the rotor slots, which does not form the rotor slots at the same rank from each of the k sets having more than three adjacent to each other, and the rotation when viewed from the rotation axis. Having a rotor slot position readjustment step that adjusts the position of the rotor slot so that the overlap angle of each of the plurality of conductor bars adjacent to each other that remains as a result of the thinning step of forming the child slot is reduced. It is characterized by.

According to the present invention, in a cage-type induction rotary electric machine having a massive rotor, it is possible to suppress an increase in the surface temperature of the rotor core portion of the massive rotor while reducing the cost increase.

It is a vertical cross-sectional view which shows the structure of the squirrel-cage induction rotary electric machine which concerns on embodiment. It is sectional drawing which shows the massive rotor and the stator slot of the squirrel-cage induction rotary electric machine which concerns on embodiment. It is a flow chart which shows the procedure of the design method of the squirrel-cage induction rotary electric machine which concerns on embodiment. It is a flow chart which shows the procedure of the design stage of the dense type rotor in the design method of the cage type induction rotary electric machine which concerns on embodiment. It is a graph which shows the trial calculation example of the relationship between the number of rotor slots, the generated stress and the loss in the dense rotor of the squirrel-cage induction rotary electric machine which concerns on embodiment. It is 1st conceptual part cross-sectional view for demonstrating the relationship between the stator slot and the rotor slot of the squirrel-cage induction rotary electric machine which concerns on embodiment. It is the 2nd conceptual part cross-sectional view for demonstrating the relationship between the stator slot and the rotor slot of the squirrel-cage induction rotary electric machine which concerns on embodiment. FIG. 3 is a cross-sectional view of a third conceptual part for explaining the relationship between the stator slot and the rotor slot of the squirrel-cage induction rotary electric machine according to the embodiment. It is a partial cross-sectional view explaining the rotor slot inclination angle of the dense type rotor which concerns on embodiment. FIG. 5 is a conceptual partial cross-sectional view illustrating the effect of the dense rotor according to the embodiment. It is a conceptual graph for demonstrating the relationship between the rotor slot inclination angle of the dense rotor which concerns on embodiment, and the evaluation function value. It is a flow chart which shows the procedure of the design stage of a massive rotor in the design method of the squirrel-cage induction rotary electric machine which concerns on embodiment. It is a partial cross-sectional view explaining the thinning-out step of rotor slot formation in the design stage of a massive rotor in the design method of the squirrel-cage induction rotary electric machine which concerns on embodiment. FIG. 5 is a partial cross-sectional view illustrating a step of readjusting the rotor slot position after thinning out the rotor slot formation in the design stage of the massive rotor in the design method of the squirrel-cage induction rotary electric machine according to the embodiment. It is a graph which conceptually explains the effect of the design method of a massive rotor in the design method of the squirrel-cage induction rotary electric machine which concerns on embodiment.

Hereinafter, the design method of the squirrel-cage induction rotary electric machine, the massive rotor, and the squirrel-cage induction rotary electric machine according to the present invention will be described with reference to the drawings. Here, parts that are the same as or similar to each other are designated by a common reference numeral, and duplicate description will be omitted.

FIG. 1 is a vertical cross-sectional view showing the configuration of a squirrel-cage induction rotary electric machine according to an embodiment.

The cage-shaped induction rotary electric machine 100 has a massive rotor 10, a stator 20, a bearing 30, a frame 40, and a cooler 51.

The massive rotor 10 is a massive magnetic pole type rotor in which a rotor core is integrated with a rotor shaft for the purpose of further improving mechanical strength, and is an integrated rotor 11, a plurality of conductor bars 16, and two. It has a short-circuit ring 17.

The integrated rotor 11 has a shaft portion 12 which corresponds to a rotor shaft and a rotor core portion 13 which corresponds to a rotor core, and these are coaxially integrated. That is, the integrated rotor 11 has a shape that is a combination of cylindrical shapes having different diameters in the rotation axis direction (hereinafter, axial direction). Around the center of the integrated rotor 11 in the axial direction, a columnar shape having a large diameter forms a rotor core portion 13. Shaft portions 12 having a diameter smaller than that of 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 of the integrated rotor 11 in the axial direction are rotatably supported by bearings 30, respectively. An inner fan 18 is provided in a portion between the rotor core portion 13 and the bearing 30 of each shaft portion 12.

The plurality of conductor bars 16 penetrate the vicinity of the radial surface of the rotor core portion 13 at intervals in the circumferential direction and extend in the axial direction. Each conductor bar 16 projects to both outer sides of the rotor core portion 13 in the axial direction. On the outer side of each of the rotor core portions 13 in the axial direction, the plurality of conductor bars 16 on the same side protrude from each other by the same length. Further, the plurality of conductor bars 16 are electrically and mechanically coupled to each other by electrically and mechanically coupling the ends of the plurality of conductor bars 16 to the annular short-circuit ring 17. While the material of the rotor core portion 13 is steel or low alloy steel, the conductor bar 16 and the short-circuit ring 17 are made of a material having a higher conductivity than the rotor core portion 13 such as copper or aluminum. It is used.

The stator 20 has a stator core 21 and a plurality of stator windings 24. The stator core 21 is provided on the radial outer side of the rotor core portion 13 of the massive rotor 10 via an annular gap 25. The stator core 21 has a cylindrical shape, 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. Bearing brackets 35 are provided at both ends of the frame 40 in the axial direction. Each of the bearing brackets 35 statically supports the bearing 30.

A cooler 51 is provided above the frame 40 and is housed in the cooler cover 52. The cooler cover 52 forms a closed space 61 together with the frame 40 and the two bearing brackets 35. The inside of the closed space 61 is filled with a cooling gas such as air, and the cooling gas circulates in the closed space 61 by the inner fan 18. The space inside the cooler cover 52 and the space inside the frame 40 constituting the closed space 61 are the cooler inlet opening 62 formed above the stator 20 and the cooling formed above the respective inner fans 18. It communicates with the vessel outlet opening 63.

FIG. 2 is a cross-sectional view showing the massive rotor 10 and the stator slot of the squirrel-cage induction rotary electric machine according to the embodiment.

A plurality of groove-shaped rotor slots 14 having a width d extending in the axial direction are formed on the radial surface of the rotor core portion 13 so as to be spaced apart from each other in the circumferential direction. A conductor bar 16 penetrates through each rotor slot 14. Each rotor slot 14 has an outer wall 14a, an inner wall 14b, and a radial innermost wall 14c that extend axially and face each other and are parallel to each other. 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 slot 14 is formed to a depth of up to the inscribed circle 14d.

The shapes and dimensions of the cross sections of the conductor bar 16 and the rotor slot 14 are almost the same as each other. The conductor bar 16 has a flat plate shape that is long in the axial direction. The conductor bar 16 can be fitted into the rotor slot 14 from the outside in the radial direction of the rotor slot 14. In order to prevent the conductor bar 16 from coming off from the rotor slot 14, for example, the portions of the conductor bar 16 facing the outer wall 14a, the inner side wall 14b, and the innermost wall 14c are wrapped with silver wax foil, and then the rotor slot 14 is used. It can be inserted and melted. Alternatively, a method may be adopted in which the conductor bar 16 is inserted into the rotor slot 14 and then TIG welding is performed from the outside, or the conductor bar 16 and the rotor slot 14 are pressed against each other.

The radial outer end of each of the plurality of conductor bars 16 has a shape that becomes a part of a cylindrical shape that wraps the radial outer surface of the rotor core portion 13, that is, the radial outer side of the rotor core portion 13. It is formed in a shape that is continuous with the surface. It should be noted that the present invention is not limited to this, and for example, the radial outer side is partially retracted radially inward from the above cylindrical shape by making the radial outer end of the conductor bar perpendicular to both sides of the conductor bar. It may be the case.

The conductor bar 16 has been described as an example in which the conductor bar 16 can be fitted into the rotor slot 14 from the outside in the radial direction of the rotor slot 14, but it can also be inserted from the axial end of the rotor core portion 13. good. In this case, the conductor bar 16 is not flat, but has a maximum thickness or a minimum thickness in the middle of the width direction, and the cross-sectional shape of the rotor slot 14 is also formed so as to fit with the conductor bar 16. It may be made to resist centrifugal force.

The rotor slot 14 is not formed along the direction outward from the rotation axis in the radial direction, but is inclined in the circumferential direction. The angle of each conductor bar 16 housed in the rotor slot 14 in the circumferential direction when viewed from the rotation axis Z of the massive rotor 10 is defined as the inscribed angle Ψ1. Further, the angle in the circumferential direction when the region in the circumferential direction in which the conductor bar 16 does not exist is viewed from the rotation axis Z of the massive rotor 10 is defined as the inscribed angle Ψ2.

Here, in the massive rotor 10 of the present embodiment, the existing regions and the non-existing regions of the conductor bars 16 are alternately arranged in the circumferential direction when viewed from the rotation axis Z, and the arrangement is as follows. There are various characteristics.

The first feature is that a plurality of conductor bars 16 are adjacent to each other in the circumferential direction in the circumferential region where the conductor bars 16 exist. The regions of the inscribed angle Ψ1 of each conductor bar 16 are adjacent to each other so as not to be separated from each other and to overlap each other. That is, when viewed from the rotation axis Z, the conductor bars 16 adjacent to each other are sequentially arranged for each inscribed angle Ψ1.

The second feature is that the following equation (1) holds.

Inscribed angle Ψ1> Inscribed angle Ψ2… (1)
If there is the above-mentioned second feature, the condition for the first feature may be relaxed. That is, the regions of the inscribed angle Ψ1 of the conductor bars 16 adjacent to each other may partially overlap each other.

As a result of forming the rotor slots 14, the same number of rotor teeth 15 as the rotor slots 14 are formed so as to be arranged at intervals in the circumferential direction.

On the radial inner surface of the stator core 21 arranged radially outward through the gap 25, a plurality of groove-shaped stator slots 22 arranged at intervals in the circumferential direction and extending in the axial direction are provided. It is formed. As a result, the same number of stator teeth 23 as the stator slots 22 are formed so as to be spaced apart from each other in the circumferential direction. The direction of the stator teeth 23 is formed so that the virtual surface 22s, which is the center of the side walls of the stator slots 22 facing each other, passes through the rotation axis Z of the massive rotor 10. The stator winding conductor 24a penetrates each stator slot 22, and the stator winding conductor 24a forms the stator winding 24.

FIG. 3 is a flow chart showing the procedure of the design method of the squirrel-cage induction rotary electric machine according to the embodiment.

The design method of the cage-type induction rotary electric machine includes a design stage S100 of the dense rotor 90 and a design stage S200 of the massive rotor 10. Here, the dense rotor 90 refers to an intermediate stage in the process of deriving the massive rotor 10 according to the present embodiment.

FIG. 4 is a flow chart showing the procedure at the design stage of the dense rotor 90 (FIG. 9). That is, the procedure of the design method for evaluating the optimum range of the circumferential pitch and the tilt angle Φ (hereinafter, the rotor slot tilt angle Φ) of the rotor slot 14 and obtaining the dense rotor 90 is shown. ..

First, the conditions of the stator slot 22 such as the dimensions of the stator slot 22 and the pitch in the circumferential direction are set (step S101). The dimensions of the stator winding conductor 24a penetrating the stator slot 22 are also set according to the setting of the conditions.

Next, the conditions of the rotor slot 14 such as the dimensions of the rotor slot 14 and the pitch in the circumferential direction are set (step S102).

Next, the rotor slot tilt angle Φ is set (step S103). The dimensions and shape of the conductor bar 16 penetrating the rotor slot 14 are also set according to the setting of the conditions.

Except for the conditions related to the rotor slot 14 and the stator slot 22, the conditions such as the dimensions of the dense rotor 90, the stator 20 and the gap 25 are assumed to be set in advance.

As a result of the above, the conditions for the rotor slot 14 and the stator slot 22 are determined. Next, the loss in the rotor core portion 13 of the dense rotor 90 is calculated (step S104). Subsequently, the temperature distribution of the rotor core portion 13 is calculated based on the calculated loss (step S105).

Further, in parallel with the temperature calculation in steps S104 and S105, the stress distribution of the rotor core portion 13 is calculated (step S106).

Next, it is determined whether or not the procedure up to step S106 has been completed over the range to be examined for the rotor slot inclination angle Φ (step S107). Here, assuming that the range to be examined for the rotor slot inclination angle Φ is the range from Φsmin to Φsmax, Φsmin is an angle larger than 0 degrees and Φsmax is an angle smaller than 90 degrees. Specifically, for example, Φsmin may be 10 degrees, Φsmax may be 80 degrees, and the like may be a wide range to some extent, or the range may be further narrowed.

If it is determined that the procedure up to step S106 has not been completed over the range to be examined for the rotor slot tilt angle Φ (step S107 NO), the process returns to step S103 and the rotor slot tilt angle Φ is changed. The steps up to step S106 are carried out.

If it is determined that the procedure up to step S106 has been completed over the range to be examined for the rotor slot tilt angle Φ (YES in step S107), then the step is performed over the range to be examined for the pitch of the rotor slot 14. It is determined whether or not the procedure up to S106 is completed (step S108). If it is determined that the procedure up to step S106 has not been completed over the range to be examined regarding the pitch of the rotor slot 14 (step S108 NO), the process returns to step S102 and the pitch of the rotor slot 14 is changed. Step S106 is carried out.

When it is determined that the procedure up to step S106 has been completed over the range to be examined for the pitch of the rotor slot 14 (step S108 YES), the process proceeds to the next step S110.

Further, the evaluation function is determined by the stage of step S110 (step S109). The evaluation function is, for example, the evaluation function PI (n) as shown in the following equation (3) or equation (4) for minimizing the total generated stress and loss with respect to the number of rotor slots n, or the evaluation function. _{It is an evaluation function PI (Φ, n 0} ) as shown by the equation (5) described later for minimizing the total generated stress and loss.

Next, the number of rotor slots n and the rotor slot tilt angle Φ of the rotor slot 14 are determined based on the evaluation function set in step S109 (step S110).

The procedure of the design method of the dense rotor 90 shown in FIG. 4 has been described above, but the procedure of steps S102 to S108 includes the examination range of the predetermined rotor slot inclination angle Φ and the rotor slot 14. This is a survey within the examination range of the pitch or the number of rotor slots n corresponding thereto. Actually, the number of rotor slots n and the rotor slot inclination angle Φ of the rotor slot 14 are determined in steps S109 and S110 based on the survey results. The contents at this stage will be described below.

FIG. 5 is a graph showing a trial calculation example of the relationship between the number of rotor slots and the generated stress and loss in the dense rotor 90. The horizontal axis represents the ratio of the number of rotor slots n to the reference number of rotor slots n _0. The vertical axis is the ratio of generated stress based on the generated stress at the reference number of rotor slots n ₀ (relative value) and the ratio of loss based on the loss at the reference _{number of rotor slots n 0 (relative value).} ).

The curve shown by the dotted line shows the case where the slot width d of the rotor slot 14 is changed in inverse proportion to the number of slots of the rotor slot 14. The curve shown by the alternate long and short dash line shows the case where the slot width d of the rotor slot 14 is fixed. Here, the generated stress indicates the stress at the base of the rotor teeth 15, which is the maximum in the stress distribution.

As shown in FIG. 5, when the number of slots of the rotor slot 14 is increased, even if the slot width d is reduced according to the increase in the number of slots, the degree of increase is alleviated, but the stress is increased. ..

The curve shown by the solid line represents the ratio (relative value) of the loss based on the loss at the reference _{rotor slot number n 0.} As shown in FIG. 5, the loss decreases as the number of rotor slots 14 increases. This point will be supplemented below with reference to FIGS. 6 to 8.

FIG. 6 is a cross-sectional view of the first conceptual part for explaining the relationship between the stator slot and the rotor slot of the cage-shaped induction rotary electric machine, and FIG. 7 is a cross-sectional view of the second conceptual part. 8 is a cross-sectional view of the third conceptual part. In each case, the display of the stator winding conductor 24a (FIG. 2) is omitted. Further, the curved line shown by the broken line in each conceptually shows the state at a certain moment of the distribution of the magnetic flux generated by the stator winding 24 (FIG. 1).

Now, let n be the number of rotor slots 14 and N be the number of stator slots 22. FIG. 6 shows a case where the number of rotor slots n is equal to the number of stator slots N. The circumferential intensity distribution (circumferential magnetic flux intensity distribution) of the magnetic flux formed by the current flowing through the stator winding 24 is a phase pitch corresponding to the distribution of the positions of the stator slots 22, in other words, a period. Therefore, for example, when the circumferential magnetic flux intensity distribution shown by the broken line in FIG. 6 occurs, it is the rotor of the conductor bar 16 that corresponds to the magnetic flux formed by the current flowing through the stator winding 24 (FIG. 1). It is a portion far from the surface of the iron core portion 13. Since the magnetic flux due to the stator winding 24 becomes weaker toward the inner side in the radial direction of the rotor core portion 13, the interaction between the magnetic flux due to the stator winding 24 and the conductor bar 16 becomes weaker, and the cage-shaped induction rotary electric machine 100 Causes a decrease in efficiency.

When the number of rotor slots n is smaller than the number of stator slots N, the time in which the interaction between the magnetic flux and the conductor bar 16 is weak further increases.

The second conceptual diagram of FIG. 7 shows a case where the number of rotor slots n is larger than the number of stator slots N. In this case, the pitch of the arrangement 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 phase. Therefore, the time in which the magnetic flux permeates the conductor bar 16 in the portion close to the surface of the rotor core portion 13, that is, the time in which the interaction between the magnetic flux and the conductor bar 16 is strong always increases.

The third conceptual diagram of FIG. 8 shows a case where the number of rotor slots n is further increased and becomes twice the number of stator slots N. In this case, the magnetic flux always permeates the portion of the conductor bar 16 close to the surface of the rotor core portion 13 in any phase, and the interaction between the magnetic flux and the conductor bar 16 continues to be strong.

As described above, when the number of rotor slots n for the rotor slot 14 is increased from the case where it is equal to the number of stator slots N for the stator slot 22 to the case where it is doubled, the stator winding 24 (FIG. 1) It is considered that the coupling between the magnetic flux generated by the above and the conductor bar 16 of the dense rotor 90 becomes stronger. This is a factor in reducing the loss.

From the above, regarding the loss, it is preferable that the number of rotor slots n is larger than the number of stator slots N, and the condition of the following equation (2) is set to be satisfied.

n / N ≧ 1.1 ・・・ (2)
As described above, the generated stress tends to increase as the number of rotor slots n of the rotor slots 14 increases, while the loss tends to decrease. That is, the generated stress and the loss tend to be opposite to each other as the number of slots of the rotor slot 14 increases.

Although the generated stress and loss are characteristic values that differ from each other, they all agree that they are negative factors. Therefore, these two negative factors are converted into evaluation criteria common to each other, that is, they are shared with each other to minimize the negative factors as a whole.

_{Now, let S 0 be} the stress generated when the number of rotor slots is n ₀ _{, and let L 0} be the loss. Here, n ₀ is arbitrary. Further, the stress generated when the number of rotor slots is n is S (n), and the loss is L (n).

At this time, for example, by minimizing the first evaluation function PIN (n) shown in the following equation (3) with respect to n, it is possible to obtain the number of rotor slots that minimizes the total generated stress and loss. can.

PIN (n) = [S (n) / S ₀ ] + p · [L (n) / L ₀ ] ... (3)
Alternatively, the first evaluation function PIN (n) shown in the following equation (4) may be used.

PIN (n) = [S (n) / S ₀ ] · [L (n) / L ₀ ] ^p ... (4)
_{S 0} and L ₀ in the formulas (3) and (4) are arbitrary reference values. Further, the constant p is a constant for considering the mutual weight of the disadvantage due to the generated stress S (n) and the disadvantage due to the loss L (n), and is the purpose of the target rotating electric machine, the design margin, etc. Set in consideration of.

As described above, for the evaluation of the number of rotor slots n as the first step, a specific value is calculated so that the above equation (3) or equation (4) is minimized. In this case, considering the process of determining the rotor slot tilt angle Φ (FIG. 9) in the next second step, the rotor slots that match the optimum conditions as a combination of the number of rotor slots n and the rotor slot tilt angle Φ. It does not always give a number. Therefore, the number of rotor slots n is selected with a sufficient width.

FIG. 9 is a partial cross-sectional view illustrating the rotor slot inclination angle Φ of the dense rotor 90 according to the embodiment. Now consider a virtual surface 14s located in the same rotor slot 14 between the outer wall 14a and the inner wall 14b facing each other and parallel to each other. Further, the surface of the rotor core portion 13 in the radial direction is defined as a curved surface Sf. Further, the line of intersection between the curved surface Sf and the virtual surface 14s is defined as the line of intersection L0. Further, a plane passing through the rotor rotation shaft 11a and the line of intersection L0 is defined as a plane P.

As a result, two planes, the virtual plane 14s and the plane P, pass through the line of intersection L0. The angle of intersection of these two planes in the circumferential direction is defined as the rotor slot tilt angle Φ. However, 0 degree <rotor slot tilt angle Φ <90 degree. Further, the angle formed by the plane P1 and the plane P2 passing through the line of intersection L1 and the line of intersection L2 adjacent to each other is defined as the pitch angle ΔΘr. However, 0 degree <pitch angle ΔΘr <90 degree.

As described above, in the dense rotor 90 of the cage-shaped induction rotary electric machine 100 according to the present embodiment, the rotor slot 14 formed on the surface of the rotor core portion 13 of the dense rotor 90 is located in the circumferential direction. It is tilted. Further, the ratio of the number of rotor slots 14 to the number of stator slots 22 is larger than 1.1.

FIG. 10 is a conceptual partial cross-sectional view illustrating the effect of the dense rotor. The two on the left side of the figure are the rotor slot 14 and the conductor bar 16 of the rotor core portion 13 according to the present embodiment. Further, on the right side, for comparison, a conventional rotor slot and a conductor bar having the same cross-sectional area as the conductor bar of the present embodiment are shown by broken lines.

The radius of the inscribed circle 14d of the rotor slot 14 in the present embodiment is larger than the radius of the inscribed circle Si0 of the conventional rotor slot. That is, the radial width ΔR1 of the rotor slot 14 according to the present embodiment is smaller than the radial width ΔR0 of the conventional rotor slot. Therefore, for example, the center position of each conductor bar 16 is close to the surface of the rotor core portion 13 as a whole, and the distance between the overall position (center position, etc.) in each conductor bar 16 and the stator winding 24. Is relatively short. ΔR1 is approximately ΔR0 · cosΦ.

In general, iron loss occurs in the rotor core portion 13 having a relatively low conductivity as compared with the conductor bar 16, and the induced current flows particularly to the surface of the rotor core portion 13, so that the rotor core portion 13 has an iron loss. The temperature of the surface of the portion 13 tends to rise.

The relatively short distance between the overall position of the conductor bar 16 and the stator winding 24 increases the coupling force due to the magnetic flux passing through the stator core 21 side and the conductor bar 16 and improves efficiency. Bring. 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 can be suppressed to be lower than in the conventional case. The larger the rotor slot tilt angle Φ, the greater this effect.

As a guideline for ensuring this effect, it is necessary to evaluate including the stator winding 24, but the ratio of the radial widths of the rotor slots 14 is, for example, at least about 5% to 10%. It seems that it needs to be reduced. In this case, the value of cosΦ is 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.

Also, if it is reduced by about 20% to 30%, it is considered to be sufficiently effective. In this case, from ΔR1 = ΔR0cosΦ, the value of cosΦ is 0.7 to 0.8, that is, Φ is 37 degrees to 46 degrees. Therefore, it is considered that the preferable rotor slot inclination angle Φ is about 40 degrees to 45 degrees.

In FIG. 10, the centrifugal force F acting on the center of gravity M in the cross section of the conductor bar 16 is a component force Fh in the direction of pulling out the conductor bar 16 along the rotor slot 14, and the outer wall of the rotor slot 14 perpendicular to the component force Fh. It is decomposed into a component force Fw in the direction of acting on 14a.

The value of the component force Fh is FcosΦ, which is smaller than the value of the centrifugal force F. Therefore, when the same level of pop-out prevention measures as before is taken, the amount of (F-FcosΦ) is a margin for pop-out prevention. Furthermore, what used to require large-scale equipment such as pressure welding does not require such large-scale equipment. For example, there may be cases where the same level of margin for pop-out prevention as before can be secured by measures to prevent pop-out such as brazing.

On the other hand, the value of the component force Fw in the direction acting on the outer wall 14a is FsinΦ, and acts so as to bend the rotor teeth 15 in the circumferential direction and the rotor teeth 15 in the radial direction. In this case, the stress distribution for the rotor teeth 15 produces a maximum value Smax at the base 15c of the rotor teeth 15. Therefore, the maximum value Smax is set to the rotor slot tilt angle within a range sufficiently smaller than the allowable stress.

As described above, in the dense rotor 90 according to the present embodiment, by tilting the rotor slot 14 in the circumferential direction, the rotor is relaxed while relaxing the conditions for preventing the conductor bar 16 from coming off from the rotor slot 14. The loss L, which causes an increase in the surface temperature of the iron core portion 13, can be suppressed.

Further, as described in the equation (2), the efficiency is further improved by setting the number of the rotor slots 14 to be larger than 1.1 times the number of the stator slots 22. Therefore, it is possible to further suppress an increase in the surface temperature Ts of the rotor core portion 13.

FIG. 11 is a conceptual graph for explaining the relationship between the rotor slot tilt angle of the dense rotor 90 and the evaluation function value according to the embodiment. The horizontal axis is the rotor slot tilt angle Φ. _{The vertical axis shows the evaluation value of the loss L (Φ, n 0} ) shown by the curve A0, the generated stress S (Φ, n ₀ ) shown by the curve B0, and the disadvantage evaluation function PIΦ (Φ) shown by the combined curve C0. , N ₀ ) function value.

The generated stress S (Φ, n ₀ ) and the loss L (Φ, n ₀ ) are values with respect to the rotor slot inclination angle Φ when the number of rotor slots is n _0.

The disadvantage evaluation function PIΦ (Φ, n ₀ ) is expressed by the following equation (5).

PIΦ (Φ, n ₀ ) = g [S (Φ, n ₀ ), L (Φ, n ₀ )]… (5)
Here, n ₀ is a value within the range of the number of rotor slots n obtained in the first step, that is, the minimization step of the equation (3) or the equation (4) with respect to the number of rotor slots n. , Treated as a parameter. That is, in the second step, that is, in the step of minimizing the disadvantage evaluation function with respect to the rotor slot inclination angle Φ, each is treated as a constant value. As a result, disadvantages evaluation function PIΦ (Φ, n ₀₎ for each rotor slot number n ₀ Kumiawase of minimizing (number rotor slot n ₀₎ and (rotor slot inclination angle Fai) is obtained. Among these combinations, the combination that minimizes the value of the disadvantage evaluation function PIΦ (Φ, n ₀ ) should be finally determined (rotor slot number n) and (rotor slot tilt angle Φ). It becomes.

The following equation (6) is used as PIΦ (Φ, n _0).

PIΦ (Φ, n ₀ ) = [S (Φ, n ₀ ) / S ₀ ] + q · [L (Φ, n ₀ ) / L ₀ ]
… (6)
As the evaluation function PI (n), the one shown in the following equation (7) may be used.

PIΦ (Φ, n ₀ ) = [S (Φ, n ₀ ) / S ₀ ] · [L (Φ, n ₀ ) / L ₀ ] ^q ... (7)
S ₀ and L ₀ are arbitrary reference values. Further, the constant q is a constant for considering the mutual weight of the disadvantage due to the generated stress S (n) and the disadvantage due to the loss L (n), as in the case of p in the first step, and is a target. Set in consideration of the purpose of the rotating electric machine or the design margin.

As described above, the equations (3) and (4) in the first step and the equations (6) and (7) in the second step are examples and are not limited thereto. That is, if there is another index affected by the rotor slot 14 tilt angle Φ, it may be added to the variables of these equations. If the effect is negligible, it may be excluded from the variable in equation (2). Further, a function shape other than the above-mentioned form may be used.

As shown in FIG. 11, as the rotor slot tilt angle Φ increases, the loss L (Φ, n ₀ ) decreases. On the other hand, the force acting on the outer wall 14a to bend the rotor teeth 15 in the circumferential direction increases as the rotor slot tilt angle Φ increases, so that the generated stress increases as the rotor slot tilt angle Φ increases. S (Φ, n ₀ ) increases. As shown in the curve C0, PIΦ (Φ, n ₀ ) has a characteristic of increasing after a decrease with respect to an increase in the rotor slot inclination angle Φ, and has a minimum value.

Further, if the condition that the loss L (Φ, n ₀ ) is equal to or less than the limit value HL is imposed and the rotor slot tilt angle Φ at this time is Φ0 min, the range of Φ> Φ0 min and the rotor slot tilt angle Φ is set. Restrict. Here, as the limit value HL, for example, a loss L that gives the maximum temperature obtained by subtracting a predetermined margin from the upper limit of the temperature range in which the operation of the rotor core portion 13 can be continued is used.

Further, if the generated stress S (Φ, n ₀ ) is subject to the condition of the limit value HS or less and the rotor slot tilt angle Φ at this time is Φ0max, the range of Φ <Φ0max and the rotor slot tilt angle Φ. To limit. Here, as the limit value HS, for example, a value obtained by subtracting a predetermined margin from the allowable stress of the material of the rotor core portion 13 is used.

If the rotor slot tilt angle Φ satisfying the condition of Φ0min <Φ <Φ0max has the minimum value as shown by the solid line C0 in the example of FIG. 11, the rotor slot tilt angle Φ0 that gives it is obtained. Looking at the predetermined angular width ΔΦ, the range from (Φ0−ΔΦ) to (Φ0 + ΔΦ) is set as the optimum range. Here, the angle width ΔΦ may be set to a value of, for example, about 5 degrees to 10 degrees, which is sufficiently larger than the manufacturing accuracy of the squirrel-cage induction rotary electric machine 100 including the formation of the rotor slot 14.

As described above, in the dense rotor 90 according to the present embodiment, by tilting the rotor slot 14 in the circumferential direction, the rotor is relaxed while relaxing the conditions for preventing the conductor bar 16 from coming off from the rotor slot 14. The increase in the surface temperature Ts of the iron core portion 13 can be suppressed, and further, the efficiency is further improved by setting the number of rotor slots 14 to be larger than 1.1 times the number of stator slots 22. .. Therefore, it is possible to further suppress an increase in the surface temperature Ts of the rotor core portion 13.

Further, the number n of the rotor slots 14 and the inclination angle Φ of the rotor slots 14 are set to the optimum values based on indexes such as the generated stress S (Φ, n ₀ ) and the loss L (Φ, n _0). be able to.

Next, the procedure of the design stage S200 of the massive rotor 10 based on the dense rotor 90 obtained in the design stage S100 of the dense rotor 90 will be described.

FIG. 12 is a flow chart showing the procedure of the design stage S200 of the massive rotor 10 in the design stage of the squirrel-cage induction rotary electric machine according to the embodiment. In the design step S200 of the massive rotor 10, the procedure for obtaining the massive rotor 10 according to the present embodiment is carried out based on the dense rotor 90 obtained in the design step S100 of the dense rotor 90.

The design stage S200 of the massive rotor 10 includes a thinning step S201 for forming the rotor slot and a readjustment step S202 for the rotor slot position after the thinning.

FIG. 13 is a partial cross-sectional view illustrating the thinning step S201 of rotor slot formation at the design stage of the massive rotor 10 in the design method of the squirrel-cage induction rotary electric machine according to the embodiment. (A) shows the state before thinning, that is, the dense rotor 90. (B) shows the state after thinning out.

In the rotor slot forming thinning step S201, a part of the rotor slot 14 formed in the dense rotor 90 obtained in the design step S100 of the dense rotor 90 is removed, that is, the rotor slot 14 is removed. Stop forming. This operation is referred to as thinning out of rotor slot formation.

The thinning of the rotor slot formation shall be performed regularly, and among the k rotor slots 14 that are continuously arranged in the 90-circumferential direction of the dense rotor, the rotor slots 14 at the same rank positions are thinned out. It shall be. For example, the first rotor slot 14 is thinned out counterclockwise. However, k is assumed to be 3 or more. That is, in FIG. 13, k is 3, and when the pairs composed of C1, C2, and C3 are arranged in the circumferential direction, C1 is thinned out for each pair.

In this way, the same operation is sequentially performed for the set composed of the k rotor slots 14. Since the last set may not be k, if the number of rotor slots 14 in the last set is one, it is not thinned out, and if there are two or more, the rotor slots 14 of C1 are similarly used. It shall be thinned out. As a result, the rotor slots 14 to be thinned out exist at the same intervals in the circumferential direction except for the last set.

In the dense rotor 90, the conductor bars 16 remaining as a result of the thinning step S201 of rotor slot formation have an inscribed angle of Ψ1 as seen from the rotation axis Z (FIG. 2) and are adjacent to each other as seen from the rotation axis Z. Let the overlapping angle of the conductor bars 16 be ΔΨ1. At this time, with respect to the portion where the rotor slot 14 is thinned out, the inscribed angle Ψd of the portion where the conductor bar 16 does not exist when viewed from the rotation axis Z is (Ψ1-2ΔΨ1).

As a result of the above, the number of rotor slots 14 is reduced to about (k-1) / k, and the cost required for forming the rotor slots 14 is reduced.

FIG. 14 is a partial cross-sectional view illustrating the readjustment step S202 of the rotor slot position after thinning in the design stage S200 of the massive rotor in the design method of the squirrel-cage induction rotary electric machine according to the embodiment. (A) shows the state after thinning out, which is the same state as (b) in FIG. FIG. 14B shows a state after the rotor slot position has been readjusted.

In the main rotor slot position readjustment step S202, the position of the rotor slot 14 is further readjusted from the result obtained in the thinning step S201 of the rotor slot formation. The readjustment method is performed by reducing the overlapping angle of the circumferential angles Ψ1 of the conductor bars 16 adjacent to each other as seen from the rotation axis Z from the overlapping angle ΔΨ1. In this case, the overlap angle is reduced to zero, but it may be reduced to an intermediate angle that is not reduced to zero. When reduced to zero, the inscribed angles Ψ1 of the conductor bar 16 as seen from the axis of rotation Z (Fig. 2) are adjacent to each other. When is performed until becomes zero, the remaining (k-1) rotor slots 14 in each set have 0 overlapping portions (k-2) before the position readjustment. By this amount, the inscribed angle of the region where the conductor bars 16 adjacent to each other as seen from the rotation axis Z cannot be seen is reduced.

That is, in the region where the conductor bars 16 adjacent to each other cannot be seen from the rotation axis Z, the following equation (9) is used between the inscribed angle Ψd before the position readjustment and the inscribed angle Ψf after the position readjustment. ) Is established.

Ψf = Ψd− (k-2) ・ ΔΨ1… (9)
By reducing the overlap angle of ΔΨ1 (reducing to zero in the case shown in FIG. 14), each conductor bar 16 is effectively used, and as a result, a highly efficient state is obtained.

FIG. 15 is a graph conceptually explaining the effect of the method of designing the massive rotor in the method of designing the squirrel-cage induction rotary electric machine according to the embodiment.

The horizontal axis is the number of rotor slots (n / n ₀ ), and the vertical axis is the cost C and the loss L.

Regarding the number of rotor slots (n / n ₀ ), as shown in the design stage S100 of the dense rotor in which the conditions of the dense rotor 90 are searched, as the number of rotor slots (n / n ₀ ) increases. , The loss of the cage-type induction rotary electric machine 100 is reduced.

On the other hand, it is clear that if the number of rotor slots (n / n ₀ ) is increased, the processing cost and the like are increased, and the cost C is increased.

Therefore, the loss L and the cost C have the property of changing in opposite directions with respect to a change in the _{number of rotor slots (n / n 0).} The characteristics of the loss L and the cost C are shown by the solid line L and the solid line C, respectively. Further, the total index of the weighting of the loss L and the cost C, which comprehensively evaluates the loss L and the cost C, is shown by a broken line (C + L).

Now, when the loss of the dense rotor 90 is L0 and the cost is C0, the condition of the dense rotor 90 is A0 on the (C + L) curve.

Thinning out of rotor slot formation By thinning out the rotor slot formation in step S201, the number of rotor slots (n / n ₀ ) is reduced, so that the cost C is lowered to C1. On the other hand, the loss increases to L1 due to the occurrence of a region in which the conductor bars 16 adjacent to each other as seen from the rotation axis Z cannot be seen. As a result, depending on the weight, the position on (C + L) becomes A1, and there is a possibility that a negative effect may occur as a whole.

Here, the loss L is reduced to L2 by readjusting the position of the rotor slot 14 in the readjustment step S202 of the rotor slot position. As a result, the total index of the weighting of the loss L and the cost C, which comprehensively evaluates the loss L and the cost C, also decreases.

That is, according to the design method of the squirrel-cage induction rotary electric machine according to the present embodiment, it is possible to obtain a massive rotor having a cost merit while maintaining the performance. That is, in a cage-shaped induction rotary electric machine having a massive rotor, it is possible to suppress an increase in the surface temperature of the rotor core portion of the massive rotor while reducing the cost increase.

[Other Embodiments]
Although the embodiments of the present invention have been described above, the embodiments are presented as examples and are not intended to limit the scope of the invention. Further, the embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The embodiments and modifications thereof are included in the scope and the gist of the invention as well as the invention described in the claims and the equivalent scope thereof.

10 ... Stator rotor, 11 ... Stator rotor, 11a ... Rotor rotation shaft, 12 ... Shaft part, 13 ... Rotor core part, 14 ... Rotor slot, 14a ... Outer wall, 14b ... Inner side wall, 14c ... Most Inner wall, 14d ... Inner circle, 14s ... Virtual surface, 15 ... Rotor tooth, 15c ... Base, 16 ... Conductor bar, 17 ... Short ring, 18 ... Inner fan, 20 ... Stator, 21 ... Stator core, 22 ... Stator slot, 23 ... Stator teeth, 24 ... Stator winding, 24a ... Stator winding conductor, 25 ... Air gap, 30 ... Bearing, 35 ... Bearing bracket, 40 ... Frame, 51 ... Cooler, 52 ... Cooler cover, 61 ... Closed space, 62 ... Cooler inlet opening, 63 ... Cooler outlet opening, 90 ... Dense rotor, 100 ... Cage-shaped induction rotor

Claims

A massive rotor used in squirrel-cage induction rotary electric machines.
A shaft part that extends in the axial direction and is rotatably supported,
A columnar rotor core portion that is integrally formed coaxially with the shaft portion, has a diameter larger than that of the shaft portion, is arranged at intervals in the circumferential direction, and has rotor slots extending in the axial direction. When,
A plurality of conductor bars penetrating the rotor slot and connecting to each other on both outer sides of the rotor core portion in the axial direction.
Have,
The two walls of the rotor slots facing each other are inclined in the circumferential direction by a predetermined angle or more with respect to the plane including the rotation axis of the shaft portion.
When the radial side is viewed from the rotation axis, a part of the existing regions and the non-existing regions of the plurality of conductor bars are alternately arranged in the circumferential direction.
A massive rotor characterized by that.
The circumference angle Ψ2 of the non-existent region when the conductor bar is viewed from the rotation axis is smaller than the circumference angle Ψ1 when each of the plurality of conductor bars is viewed from the rotation axis. Massive rotor.
The first or second aspect of the present invention, wherein the regions having an inscribed angle Ψ1 when each of the plurality of conductor bars is viewed from the rotation axis of the shaft portion are adjacent to each other so as not to overlap each other. Massive rotor.
The massive rotor according to any one of claims 1 to 3, wherein the innermost wall in the radial direction is formed in a curved surface shape in the cross section of the rotor slot.
A claim characterized in that each of the radial outer ends of the plurality of conductor bars is formed in a shape that becomes a part of a cylindrical shape that wraps the radial outer surface of the rotor core portion. The massive rotor according to any one of items 1 to 4.
The massive rotor according to any one of claims 1 to 5, wherein the predetermined angle is 20 degrees or more.
The massive rotor according to any one of claims 1 to 6 and the massive rotor.
A cylindrical stator core provided on the radial outer side of the rotor core portion, and a plurality of fixings formed on the inner surface of the stator core in the radial direction at intervals in the circumferential direction and extending in the axial direction. A stator with a stator winding that penetrates the inside of the child slot, and
Two bearings that support the massive rotor on both sides of the shaft portion in the axial direction with the rotor core portion interposed therebetween.
A squirrel-cage induction rotary electric machine characterized by being equipped with.
A method for designing a squirrel-cage induction rotary electric machine, which includes a massive rotor integrally formed and having a shaft portion and a rotor core portion, and a stator provided outside the rotor core portion in the radial direction.
A stator condition setting step for setting the dimensions and the pitch in the circumferential direction of a plurality of stator slots formed on the radial inner surface of the stator and arranged at intervals in the circumferential direction and penetrating in the axial direction.
After the stator condition setting step, the dimensions and circumferential pitch of the rotor slots formed on the radial outer surface of the rotor core portion and arranged at intervals in the circumferential direction and penetrating in the axial direction. In the dense rotor condition setting step to set the tilt angle in the circumferential direction and obtain the dense rotor,
With respect to the rotor slots of the dense rotor, the thinning step of forming the rotor slots which does not form the rotor slots at the same rank from each of k sets of more than three adjacent to each other.
A rotor slot that adjusts the position of the rotor slot so that the overlapping angles of the plurality of adjacent conductor bars remaining as a result of the thinning step of forming the rotor slot are reduced when viewed from the rotation axis. Position readjustment step and
A method of designing a squirrel-cage induction rotary electric machine, which is characterized by having.
The rotor condition setting step is
A tilt angle setting step for setting the tilt angle of the rotor slot in the circumferential direction, and
After the tilt angle setting step, a stress calculation step for calculating the stress of the rotor core portion and a stress calculation step
After the tilt angle setting step, a temperature calculation step for calculating the temperature of the rotor core portion and a temperature calculation step
It is determined whether or not the rotation angle of the rotor slot in the circumferential direction has been completed over the examination range, and when it is determined that the rotation angle has not been completed, the angle range determination step of performing the tilt angle setting step and subsequent steps is performed. ,
When it is determined in the angle range determination step that the tilt angle of the rotor slot in the circumferential direction has been completed over the examination range, it is determined whether or not the rotation range has ended over the examination range regarding the pitch of the rotor slot. , A pitch range determination step for executing the rotor condition setting step and subsequent steps when it is determined that the process has not been completed,
When it is determined in the pitch range determination step that the pitch of the rotor slot has been examined over the examination range, the inclination angle of the rotor slot and the inclination angle of the rotor slot are determined based on the results of the stress calculation step and the temperature calculation step. The decision step to determine the pitch and
The method for designing a squirrel-cage induction rotary electric machine according to claim 8, wherein the squirrel-cage induction rotary electric machine is provided.
The method for designing a squirrel-cage induction rotary electric machine according to claim 9, wherein the number of rotor slots is a predetermined ratio greater than 1 with respect to the number of stator slots.
The method for designing a squirrel-cage induction rotary electric machine according to claim 9 or 10, wherein the predetermined ratio is 1.1 or more.