TWI806115B - Rotor, cage induction motor and drive system - Google Patents

Abstract

The present invention provides a rotor of a cage-type induction motor. The size of the rotor conductor does not need to be adjusted according to the material or shape of the rotor and the frequency of the power supply. The size ratio of the rotor conductor can be kept at a fixed value, and the noise generated during the starting process can be suppressed. Torque drops.

The rotor of the present invention has a rotor conductor, and the rotor conductor has: a first part whose width in the circumferential direction of the rotor conductor gradually becomes smaller toward the inner peripheral side of the rotor conductor; and a second part which is different from the inner circumference of the first part side, and its width in the circumferential direction of the rotor conductor gradually increases toward the inner circumferential side of the rotor conductor; set the distance from the end of the outer circumferential side of the rotor conductor to the end of the inner circumferential side of the rotor conductor as h0, and set the distance from the end of the rotor conductor to the inner circumferential side of the rotor conductor The distance from the outer peripheral end to the outer peripheral end of the first part is h1, and the distance from the outer peripheral end of the rotor conductor to the inner peripheral end of the second part is h2, if the constant N is based on the starting process When the constant calculated from the depth of the eddy current penetrating into the rotor conductor at the rotation speed that produces torque drop, the rotor conductor satisfies the relationship of h1/h0<N<h2/h0.

Description

Rotor, cage induction motor and drive system

The present invention relates to a rotor.

The cage-type induction motor can be started by directly connecting to a commercial power supply, but the torque during the starting process is not a fixed value, and it may drop at a certain rotational speed, causing the acceleration to stagnate. A rotor construction is known which improves the torque characteristics during start-up of cage-type induction motors.

For example, in the rotor of the cage-type induction motor described in Patent Document 1, a plurality of rotor conductors made of a material whose resistance value increases sequentially from the outer peripheral side, and accommodating holes (rotor slots) for arranging the rotor conductors are provided in the rotor. , and the slit connecting the receiving hole (rotor slot).

The rotor of the cage-type induction motor described in Patent Document 2 has a first slot and a second slot that is located closer to the outer peripheral surface of the rotor core than the first slot and is connected to the first slot. For the skin depth of the components, the first groove is arranged on the side opposite to the side of the outer peripheral surface, and the second groove is arranged on the side of the outer peripheral surface.

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 6-205570

[Patent Document 2] WO2019/244238 Publication

In the rotor of the cage-type induction motor of Patent Document 1, although the torque drop generated during the starting process is suppressed, the radial height and circumference of the slit must be properly adjusted according to the material or shape of the rotor conductor and the frequency of the power supply. to the width.

In the rotor of the cage-type induction motor of Patent Document 2, the driving efficiency can be improved while increasing the starting torque, but the first slot and the second slot must be adjusted appropriately according to the material of the rotor conductor or the driving frequency (power frequency). The configuration location.

The object of the present invention is to provide a rotor that does not need to adjust the size of the rotor conductor according to the material or shape and the frequency of the power supply, and can suppress the torque generated during the starting process while maintaining the size ratio of the rotor conductor at a fixed value. decline.

A preferred example of the present invention is a rotor having a rotor conductor, and the rotor conductor has: a first portion whose width in the circumferential direction of the rotor conductor gradually becomes smaller toward the inner peripheral side of the rotor conductor; and a second portion whose It is connected to the inner peripheral side of the above-mentioned first part, and it is between the above-mentioned rotor conductors The width in the circumferential direction gradually increases toward the inner peripheral side of the above-mentioned rotor conductor; the distance from the end of the outer peripheral side of the above-mentioned rotor conductor to the end of the inner peripheral side of the above-mentioned rotor conductor is set as h0, and the distance from the end of the outer peripheral side of the above-mentioned rotor conductor to the end of the inner peripheral side of the above-mentioned rotor conductor is set to The distance from the end of the outer circumference of the first part above is h1, and the distance from the end of the outer circumference of the above-mentioned rotor conductor to the end of the inner circumference of the second part is h2. If the constant N is based on the When the constant is calculated from the depth of the eddy current penetrating into the above-mentioned rotor conductor at the rotation speed of the torque drop, the above-mentioned rotor conductor satisfies the following relationship: h1/h0<N<h2/h0.

According to the present invention, there is no need to adjust the size of the rotor conductor according to the material or shape and the power frequency, and the torque drop generated during startup can be suppressed while keeping the size ratio of the rotor conductor at a constant value.

1: Stator

2: Stator core

3: Stator slot

4: Stator winding

5: rotor

6: Rotor core

7: rotor slot

8: Rotor conductor

9: axis

10: Clearance

81: Part 1

82: Part 2

83: Part 3

84: Part 4

85:Part 5

86: Part 6

87: Part 7

100: cage induction motor

101: Power

102: load equipment

Fig. 1 is a cage-type induction motor as Embodiment 1 and its partial enlarged view.

Fig. 2 is a diagram showing an equivalent circuit of a cage induction motor.

Fig. 3 is a graph showing coefficients representing the influence of the skin effect.

Fig. 4 is a graph showing the rotation speed (ξ) at which torque drop occurs.

Fig. 5 is the computer experiment result of starting torque.

Figure 6 is the driving system of the cage induction motor.

7(a), (b) are diagrams showing one slot of the rotor of the cage-type induction motor of the fourth embodiment.

Fig. 8 is a view showing one slot of the rotor of the cage-type induction motor of the fifth embodiment.

Fig. 9 is a view showing one slot of the rotor of the cage-type induction motor of the sixth embodiment.

Fig. 10 is a view showing one slot of the rotor of the cage-type induction motor of the seventh embodiment.

Fig. 11 is a diagram showing one slot of the rotor of the cage-type induction motor of the eighth embodiment.

Fig. 12 is a view showing one slot of the rotor of the cage-type induction motor of the ninth embodiment.

Hereinafter, an embodiment will be described with reference to the drawings.

[Example 1]

Embodiment 1 will be described using a double cage rotor which is an example of a rotor of a cage induction motor. The left side of Fig. 1 is a diagram showing the main parts of the cage induction motor, and the right side of Fig. 1 is an enlarged view of one slot of the rotor. The cage-type induction motor of Embodiment 1 is a rotating electrical machine in which the stator 1 and the rotor 5 face each other in the radial direction R through a gap 10 .

The stator 1 includes a stator core 2 and a stator winding 4 wound in stator slots 3 formed in the stator core 2 .

The rotor 5 includes a rotor core 6 , a rotor conductor 8 disposed in a rotor slot 7 formed in the rotor core 6 , and a shaft 9 disposed on the inner peripheral side of the rotor core 6 .

As shown on the right side of FIG. 1 , the rotor conductor 8 extending in the radial direction R has: a first portion 81 whose width in the circumferential direction X of the rotor conductor 8 gradually decreases toward the inner peripheral side of the rotor conductor 8 ; and a second portion 81 . The portion 82 is connected to the inner peripheral side of the first portion 81 , and its width in the circumferential direction of the rotor conductor 8 gradually increases toward the inner peripheral side of the rotor conductor 8 . The so-called inner peripheral side refers to the lower side in the right diagram of FIG. 1 .

In the rotor conductor 8 including the first part 81 and the second part 82, assuming that the distance from the end on the outer peripheral side of the rotor conductor 8 to the end on the inner peripheral side of the rotor conductor 8 is h0, the distance from the rotor conductor 8 is When h1 is the distance from the end on the outer peripheral side to the end on the outer peripheral side of the first portion 81, and h2 is the distance from the end on the outer peripheral side of the rotor conductor 8 to the end on the inner peripheral side of the second portion 82 , satisfy the relationship of h1/h0<N<h2/h0 (N is a constant). Here, the constant N is calculated based on the depth of the eddy current penetrating into the rotor conductor 8 at the rotation speed at which the torque drops during starting. Also, the term "outer peripheral side" refers to the upper side in the right diagram of Fig. 1 .

The rotor conductor 8 is formed by pressing aluminum, for example, into the rotor slot 7 by die casting. Therefore, the rotor conductor 8 is not divided by parts (for example, slits) other than aluminum in the rotor slot 7, and has an integral structure. However, air bubbles caused by die casting may also occur in the rotor conductor 8 .

In Example 1, the first part 81 and the second part 82 are provided in the double-cage rotor. That is, the rotor conductor 8 has a third portion 83 on the outer peripheral side of the first portion 81, the rotor conductor 8 having a circumferential width smaller than the end of the outer peripheral side of the first portion 81, and the rotor conductor 8 has a fourth portion 84. The fourth part 84 is connected to the outer peripheral side of the third part 83, and its width in the circumferential direction of the rotor conductor 8 is oriented The outer peripheral side of the rotor conductor 8 gradually becomes larger.

Fig. 2 is a diagram showing an equivalent circuit of a cage induction motor. Using the equivalent circuit of the cage induction motor, derive the relationship between torque and equivalent circuit constants.

V is the phase voltage (V), I2' is the secondary current (A), r1 is the primary resistance (Ω), r2' is the secondary resistance (Ω), xM is the excitation reactance (Ω), and rM is the iron loss resistance ( Ω), x1 is primary leakage reactance (Ω), x2' is secondary leakage reactance (Ω), s is sliding (p.u.).

The secondary input P2(W) is represented by the following (Formula 1).

P2=3×I2' ² ×r2'/s (Formula 1)

The secondary copper loss W2 (W) is represented by the following (Formula 2).

W2=3×I2' ² ×r2' (Formula 2)

The output Pout(W) is a value obtained by subtracting the secondary copper loss from the secondary input, and is represented by the following (Formula 3).

Pout=P2-W2=3×I2' ² ×r2'/s-3×I2' ² ×r2'=3×I2' ² ×r2'(1/s-1)=3×I2' ² ×r2' (1-s)/s (Equation 3)

Torque T (N‧m) is the quotient obtained by dividing the output by the angular rotation speed of the rotor ω (rad/sec). It is represented by the following (Formula 4).

Here, N: rotational speed (r/min), Ns: synchronous speed (r/min) In the range of slip s where torque drop is to be improved, I2' is approximately inversely proportional to x1+x2'. Therefore, the proportional relationship of the torque T is represented by the following (Formula 5).

1與(式9)之

2，單位為(p.u.)。圖3之橫軸為ξ(等效轉子導體高度之倒數比)，單位為(p.u.)。 Fig. 3 is a graph showing coefficients representing the influence of the skin effect. The vertical axis of FIG. 3 shows the following (Formula 8) as a coefficient representing the influence of the skin effect.

1 and (Formula 9)

2. The unit is (pu). The horizontal axis of Fig. 3 is ξ (the reciprocal ratio of the equivalent rotor conductor height), and the unit is (pu).

In the range of the slip s where the torque drop is to be improved, the depth of the eddy current penetrating into the rotor conductor 8 is shallower than h0 of the rotor conductor 8 by the skin effect. Considering the influence of the skin effect, the secondary resistance r2' and the leakage reactance x are represented by the following (Equation 6) and (Equation 7).

x=x1+x2'

ξ=α×h0 (Formula 10)

α=2π(10 ^-7 ×sf/ρ) ^0.5 (Formula 11)

here,

1、

2：表示集膚效應之影響之係數(p.u.)

1,

2: Indicates the coefficient of the influence of the skin effect (pu)

r2'dc: secondary resistance of sliding zero (Ω)

xdc: Leakage reactance of sliding 0 (Ω)

K2: The ratio of secondary tank leakage to the overall leakage reactance (p.u.)

ξ: Reciprocal ratio of equivalent rotor conductor height (p.u.)

α: Indicates the number of skin depth (1/m)

h0: rotor conductor height (m)

s: slide (p.u.)

f: power frequency (Hz)

ρ: Resistivity of rotor conductor (Ω‧m)

The horizontal axis ξ of Fig. 3 is the reciprocal ratio of the electromagnetically equivalent rotor conductor height when the skin effect is considered. As shown in (Expression 11), α is small when the rotation speed is high (sliding s is small), and ξ is small when α is small, as shown in (Expression 10). Likewise, ξ is larger when the rotational speed is lower.

1與

2為1，表示無集膚效應之影響之狀態。 That is, the equivalent rotor conductor height becomes smaller as the rotation speed decreases, and becomes larger as the rotation speed increases. When the rotation speed is equal to the synchronous speed (slip is 0), α is 0 as shown in (Formula 11), and ξ becomes 0 when α is 0 as shown in (Formula 10). When ξ is 0, it represents the coefficient of skin effect

1 with

2 is 1, which means there is no influence of skin effect.

Fig. 3 shows the situation that the resistivity ρ of the rotor conductor is uniform in the rotor conductor 8, which is not applicable to the rotor of the cage-type induction motor described in Patent Document 1, for example. In the case of a plurality of rotor conductors made of materials that increase in height sequentially, or in the case of providing slits connecting the rotor slots.

The rotor conductor 8 is made of all the same material (aluminum), and is not divided by parts (such as slits) other than aluminum in the rotor slot 7 to form an integral structure. The resistivity ρ of the rotor conductor is uniform in the rotor conductor 8 .

Fig. 4 is a graph showing the rotation speed (ξ) at which torque drop occurs. The relationship between the number n(ξ) (vertical axis) and ξ (horizontal axis) when the torque T is proportional to the power of ξ is shown. Derive ξ at the rotational speed that produces a torque drop.

When (Formula 6) and (Formula 7) are substituted into (Formula 5), the proportional relationship of the torque T is expressed by the following (Formula 12).

When the torque T in (Expression 12) is proportional to the power of ξ, the proportional relationship of the torque T is expressed by the following (Expression 13).

When n(ξ) in (Formula 13) is a positive number, the torque T decreases as the rotation speed increases (ξ decreases), and when n(ξ) is negative, the torque T decreases as the rotation speed increases (ξ decreases). The torque T increases. Therefore, if there is a range where n(ξ) in (Formula 13) is a positive number, the torque will decrease.

As shown in FIG. 4 , n(ξ) may become positive when the ratio K2 of secondary tank leakage to the entire leakage reactance becomes larger. That is, if the ratio K2 of the secondary tank leakage to the entire leakage reactance increases, the torque tends to decrease.

In FIG. 4, when K2 is 0.5 or more, n(ξ) may be positive. That is, when K2 is 0.5 or more, torque will fall. When K2 is 0.5, n(ξ) becomes maximum when ξ is 2.2. K2 is a maximum of 1, and when K2 is 1, n(ξ) becomes a maximum when ξ is 2.6.

Thus, when K2 is 0.5-1.0 and ξ is 2.2-2.6, n(ξ) is relatively large (torque reduction degree is large). That is, if the torque increase is prioritized at the rotation speed at which ξ is 2.2 to 2.6, the torque drop can be effectively improved.

When the rotor conductor height h0 is set to 1.0, the skin depth δ is represented by the following (Formula 14).

δ=1/(αh0)=1/ξ (Equation 14)

When K2 is 0.5~1.0 and ξ is 2.2~2.6, the degree of torque reduction becomes larger. If ξ is 2.2 and is substituted into (Formula 14), then when ξ is 2.2, the skin depth is 0.45, and similarly for ξ When ξ is 2.6, the skin depth is 0.38, and when ξ is an average value of 2.4, the skin depth is 0.42.

The constant N (skin depth δ) is based on the rotational speed at which the torque drops during start-up Calculated from the depth of eddy current penetrating into the rotor conductor, it is within the range of 0.38 to 0.45. As a typical example of this range, a case where the constant N (skin depth δ) is 0.42 will be described.

Based on the above, in the present embodiment, in order to increase the torque preferentially at the rotational speed at which the skin depth δ is 0.42, relative to the end from the outer peripheral side of the rotor conductor 8 to the inner peripheral side of the rotor conductor 8 A constriction is set at a position where the distance h0 at the end is 0.42 times, and r2' is effectively increased to improve torque drop.

In this embodiment, the torque drop can be improved by setting the constricted portion at a position 0.42 times higher than h0, and it is not necessary to adjust the size ratio to maintain it even when the material or shape of the rotor conductor and the power frequency are changed. It can be a fixed value.

On the other hand, in general, in order to improve the torque characteristics during starting, for example, as described in Patent Document 1, it is necessary to appropriately adjust the radial height and For the circumferential width, or as described in Patent Document 2, it is necessary to properly adjust the arrangement positions of the first slot and the second slot according to the material of the rotor conductor or the driving frequency (power frequency). The idea of this embodiment is that even when the material or shape of the rotor conductor and the frequency of the power supply are changed, it is not necessary to adjust the size ratio of the rotor conductor and keep it at a fixed value, so that the torque characteristics during the starting process can be improved. However, there is no such design in Patent Document 1 and Patent Document 2.

Fig. 5 is the computer experiment result of starting torque. Shown in the present embodiment 1 of Fig. 1, when both h1/h0 and h2/h0 are less than 0.42 (when the constricted part is placed on the outer peripheral side and is relatively shallow), when both h1/h0 and h2/h0 are greater than 0.42 ( When the narrowed part is placed deeper on the inner peripheral side), when the narrowed part is not provided. The target machine has 4 poles, assuming that the rotor conductor 8 is aluminum and the resistivity ρ is 3.65×10 ^-8 Ω‧m, the rotor conductor height h0 is 51mm, and the power frequency f is 50Hz. The rated torque is set to 100%.

In this embodiment, the torque drop is improved. Compared with the case where the narrowed part is placed shallower on the outer peripheral side, the torque becomes larger on the high rotation speed side, and the case where the narrowed part is placed deeper on the inner peripheral side Compared with the time, the torque becomes larger on the low rotation speed side. Therefore, in this embodiment, the minimum value of the torque becomes larger both when the constricted portion is shallow on the outer peripheral side and when the constricted portion is deep on the inner peripheral side.

[Example 2]

Example 2 will be described. Descriptions of points common to Embodiment 1 are omitted. Cage-type induction motors are often used in the range of rotation speed from 0 to synchronous speed. The slip s is 1 when the rotation speed is 0, and the slip s is 0 when the rotation speed is equal to the synchronous speed.

Therefore, by making the slip s that causes a torque drop larger than 1, the torque drop can also be suppressed, and it can be derived as follows.

From (Formula 10), α is represented by the following (Formula 15).

α=ξ/h0 (Equation 15)

From (Equation 11), the slide s is represented by the following (Equation 16).

s=ρα ² /(4π ² ×10 ^-7 ×f) (Formula 16)

When (Formula 15) is substituted into (Formula 16), it will be represented by the following (Formula 17).

s=ρξ ² /(4π ² ×10 ^-7 ×f×h0 ² ) (Formula 17)

When the slip is greater than 1, (Equation 17) is represented by the following (Equation 18).

1<ρξ ² /(4π ² ×10 ^-7 ×f×h0 ² ) (Equation 18)

When h0 is derived from (Formula 18), it is represented by the following (Formula 19).

h0<ρ ^0.5 ×ξ/(2π×10 ^-3.5 ×f ^0.5 ) (Formula 19)

The ξ of the resulting torque drop is 2.2 to 2.6, and when 2.4, which is the average value thereof, is substituted into (Formula 19), it is expressed by the following (Formula 20).

h0<1200(ρ/f) ^0.5 (Formula 20)

Therefore, according to (Equation 20), by adjusting the height h0 of the rotor conductor according to the resistivity ρ of the rotor conductor 8 in Ω‧m and the power frequency f in Hz, the slippage s that produces torque drop can be made greater than 1 . As a result, a decrease in torque can be suppressed.

[Example 3]

Fig. 6 is a diagram showing a drive system of a cage-type induction motor as a third embodiment. The description of common points with the above-mentioned embodiments is omitted.

The cage induction motor 100 is started by directly connecting commercial voltage and commercial frequency from the power supply 101 . The cage induction motor 100 is mechanically connected to a load device 102 .

Cage-type induction motors can be started directly by connecting to a commercial power supply, but the current during start-up will be about 6 to 10 times the rated current, and the capacity of the power supply equipment is determined by the current and start-up time during start-up. By using the cage-type induction motor of the present invention, the decrease in torque can be suppressed, the start-up time can be shortened, and the capacity of power supply equipment can be reduced.

[Example 4]

Fig. 7 is a view showing one slot of the rotor of the cage induction motor of the fourth embodiment. The description of points common to the above-mentioned embodiments is omitted.

The position of the first part 81 and the second part 82 of the rotor conductor 8 is not necessarily the boundary position between the first part 81 and the second part 82 (the position where the circumferential width of the first part 81 and the second part 82 is the smallest) becomes 0.42 times the rotor conductor height h0. For example, as shown in FIG. 7( a ), the position of 0.42 times may fall on the second part 82 , or as shown in FIG. 7( b ), the position of 0.42 times may fall on the first part 81 .

In addition, the rotor conductors 8 shown in Fig. 7(a) and Fig. 7(b) may be arranged alternately in the circumferential direction. By alternately arranging them, it is possible to obtain the effect of suppressing torque drop over a wider range of rotation speeds.

[Example 5]

Fig. 8 is a view showing one slot of the rotor of the cage-type induction motor of the fifth embodiment. The description of points common to the above-mentioned embodiments is omitted.

The rotor conductor 8 has a section with a constant width in the circumferential direction between the end on the inner peripheral side of the first portion 81 and the end on the outer peripheral side of the second portion 82 . The effect of suppressing the torque drop is enhanced because the area having a smaller width in the circumferential direction becomes larger.

[Example 6]

Fig. 9 is a view showing one slot of the rotor of the cage-type induction motor of the sixth embodiment. The description of points common to the above-mentioned embodiments is omitted.

The circumferential width of the rotor conductor 8 changes stepwise between the end on the outer peripheral side of the first portion 81 and the end on the inner peripheral side of the second portion 82 . Compared with the case where the width is gradually changed, the area where the width in the circumferential direction is small becomes larger, so the effect of suppressing the torque drop is enhanced.

[Example 7]

Fig. 10 is a view showing one slot of the rotor of the cage-type induction motor of the seventh embodiment. The description of points common to the above-mentioned embodiments is omitted.

Embodiment 7 will be described using a convex rotor as an example of a rotor of a cage-type induction motor. In Example 7, the first portion 81 and the second portion 82 are provided on the convex rotor. That is, the rotor conductor 8 has a third portion 83 on the outer peripheral side of the first portion 81 , and the circumferential width of the rotor conductor 8 at the third portion 83 is smaller than the end of the first portion 81 on the outer peripheral side.

Further, the rotor conductor 8 includes a seventh portion 87 which is connected to the inner peripheral side of the third portion and whose width in the circumferential direction of the rotor conductor 8 gradually increases toward the inner peripheral side of the rotor conductor.

If the circumferential width of the rotor conductor 8 is reduced, the current when the slip is large decreases. The closer the position where the circumferential width of the rotor conductor 8 is reduced is closer to the outer peripheral side of the rotor conductor 8, the greater the effect. Therefore, compared with the double-cage rotor, the first part 81 and the second part 82 are provided on the convex rotor. It can further reduce the current when the sliding is large.

[Example 8]

Fig. 11 is a diagram showing one slot of the rotor of the cage-type induction motor of the eighth embodiment. The description of points common to the above-mentioned embodiments is omitted.

Embodiment 8 will be described using a rhomboid rotor which is an example of a rotor of a cage-type induction motor. In Example 8, the rhomboid rotor is provided with the first portion 81 and the second portion 82 . That is, the rotor conductor 8 includes a fifth portion 85 on the outer peripheral side of the first portion 81 , and the width of the fifth portion 85 in the circumferential direction of the rotor conductor 8 gradually decreases toward the outer peripheral side. The circumferential width of the end on the outer peripheral side of the fifth portion 85 is smaller than the circumferential width of the end on the outer peripheral side of the first portion 81 .

If the circumferential width of the rotor conductor 8 is reduced, the current when the slip is large decreases. The closer the position where the circumferential width of the rotor conductor 8 becomes smaller is closer to the outer circumference of the rotor conductor 8, the greater the effect. Therefore, compared with the double-cage rotor, by providing the first part 81 and the second part 82 in the rhombic rotor, It can reduce the current when the sliding is large.

[Example 9]

Fig. 12 is a view showing one slot of the rotor of the cage-type induction motor of the ninth embodiment. The description of points common to the above-mentioned embodiments is omitted.

Embodiment 9 will be described using an eggplant-shaped rotor as an example of a cage-type induction motor rotor. In Example 9, the first part 81 and the second part 82 are provided on the eggplant-shaped rotor. That is, the rotor conductor 8 includes a sixth portion 86 in which the circumferential width of the rotor conductor 8 gradually increases toward the outer peripheral side on the outer peripheral side of the first portion 81 .

The circumferential width at the end of the sixth portion 86 on the outer peripheral side is larger than the width in the circumferential direction at the end of the outer peripheral side of the first portion 81 .

If the circumferential width of the rotor conductor 8 is reduced, the power factor at the time of stable operation with little slippage is reduced. The rotor conductor 8 of the eggplant-shaped rotor has fewer intervals in the circumferential direction than the double-cage rotor, the convex rotor, and the diamond-shaped rotor. By setting the first part 81 and the second part 82 in the eggplant-shaped rotor, the sliding Hourly power factor is improved.

As mentioned above, although the Example was demonstrated, it is not limited to the said Example, Various modification examples are included. For example, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of a certain embodiment. Moreover, it is also possible to add, delete, or replace a part of the configuration of each embodiment with other configurations.

1: Stator

2: Stator core

3: Stator slot

4: Stator winding

5: rotor

6: Rotor core

7: rotor slot

8: Rotor conductor

9: axis

10: Clearance

81: Part 1

82: Part 2

83: Part 3

84: Part 4

Claims (11)

A rotor having a rotor conductor, wherein the rotor conductor is made of the same material, and has: a first portion whose width in the circumferential direction of the rotor conductor gradually decreases toward the inner peripheral side of the rotor conductor; and a second portion part, which is connected to the inner peripheral side of the first part, and its width in the circumferential direction of the rotor conductor gradually increases toward the inner peripheral side of the rotor conductor; from the end of the outer peripheral side of the above-mentioned rotor conductor to the The distance from the end on the inner peripheral side is h0, the distance from the end on the outer peripheral side of the above-mentioned rotor conductor to the end on the outer peripheral side of the first part is h1, and the distance from the end on the outer peripheral side of the above-mentioned rotor conductor to the above-mentioned second part is h1. The distance between the ends on the inner peripheral side is set to h2, and if the constant N is a constant calculated based on the depth of the eddy current penetrating into the above-mentioned rotor conductor at the rotational speed at which the torque drops during starting, the above-mentioned rotor conductor satisfies the following relationship : h1/h0<N<h2/h0; the above N is within the range of 0.38 to 0.45. The rotor according to claim 1, wherein said N is 0.42. The rotor according to claim 1, wherein the rotor conductor has a section with a constant width in the circumferential direction between the end on the inner peripheral side of the first part and the end on the outer peripheral side of the second part. The rotor according to claim 1, wherein the circumferential width of the rotor conductor at the end on the outer peripheral side of the first part and the end on the inner peripheral side of the second part changes in a step shape. The rotor according to claim 1, wherein the rotor conductor has: a third part, which is located on the outer peripheral side of the first part, and whose width in the circumferential direction of the rotor conductor is smaller than an end on the outer peripheral side of the first part; and The seventh part is connected to the inner peripheral side of the third part, and its width in the circumferential direction of the rotor conductor gradually increases toward the inner peripheral side of the rotor conductor. The rotor according to claim 1, wherein the rotor conductor has a fifth part on the outer peripheral side of the first part, and the width of the fifth part in the circumferential direction of the rotor conductor gradually becomes smaller toward the outer peripheral side, and the outer circumference of the fifth part is The circumferential width of the side end is smaller than the circumferential width of the outer circumferential end of the first portion. The rotor according to claim 1, wherein the rotor conductor has a sixth part on the outer peripheral side of the first part, and the width of the sixth part in the circumferential direction of the rotor conductor gradually increases toward the outer peripheral side, and the outer circumference of the sixth part is The circumferential width of the side end is greater than the circumferential width of the outer circumferential end of the first portion. Such as the rotor of claim 1, wherein when the resistivity of the above-mentioned rotor conductor with the unit of Ω‧m is set as ρ, and the power frequency with the unit of Hz is set as f, the above-mentioned h0 satisfies the following relationship: h0<1200( ρ/f) ^0.5 . The rotor according to claim 1, which has a rotor core, the rotor conductors are disposed in rotor slots formed in the rotor core, and a shaft is provided on the inner peripheral side of the rotor core. A cage induction motor having the rotor of claim 1. A drive system comprising the cage-type induction motor of claim 10, a power supply, and a load device.

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