JP7419205B2 - Rotor, squirrel cage induction motor and drive system - Google Patents

Description

The present invention relates to a rotor.

Squirrel-cage induction motors can be started by directly turning on commercial power, but the torque during starting is not a constant value, and a drop occurs at a certain rotational speed, which may cause acceleration to stagnate. Rotor structures are known that improve the torque characteristics during starting of squirrel cage induction motors.

For example, the rotor of the squirrel-cage induction motor described in Patent Document 1 includes a plurality of rotor conductors made of materials whose resistance values are sequentially higher from the outer circumferential side, and an accommodation hole in which the rotor conductors are arranged. A slit is provided that connects the housing hole (rotor slot) and the housing hole (rotor slot).

The rotor of the squirrel cage induction motor described in Patent Document 2 includes a first slot and a first slot located closer to the outer peripheral surface of the rotor core than the first slot and connected to the first slot. The first slot is located on the side opposite to the outer circumferential surface, and the second slot is disposed on the outer circumferential surface side with respect to the skin depth of the drive frequency component of the current.

Japanese Patent Application Publication No. 6-205570 WO2019/244238 publication

The rotor of the squirrel cage induction motor of Patent Document 1 suppresses the drop in torque that occurs during startup, but the radial height and circumferential width of the slits are adjusted depending on the material and shape of the rotor conductor and the frequency of the power source. It is necessary to make appropriate adjustments.

The rotor of the squirrel cage induction motor of Patent Document 2 can increase the starting torque and improve the driving efficiency. It is necessary to adjust it appropriately according to the drive frequency (power frequency).

An object of the present invention is to suppress the drop in torque that occurs during startup while keeping the dimensional ratio of the rotor conductor at a constant value without adjusting the dimensions of the rotor conductor according to the material, shape, or power frequency. , to provide a rotor.

A preferred example of the present invention is a rotor having a rotor conductor,
The rotor conductor is
a first portion where the width of the rotor conductor in the circumferential direction becomes smaller toward the inner circumferential side of the rotor conductor;
a second portion that is continuous with the inner circumferential side of the first portion and the width of the rotor conductor in the circumferential direction increases toward the inner circumferential side of the rotor conductor;
The distance from the outer peripheral end of the rotor conductor to the inner peripheral end of the rotor conductor is h0,
The distance from the outer circumferential end of the rotor conductor to the outer circumferential end of the first portion is h1,
The distance from the outer peripheral end of the rotor conductor to the inner peripheral end of the second portion is h2,
The rotor conductor is
The rotor satisfies the relationship h1/h0<N<h2/h0 (N is a constant of 0.38 or more and 0.45 or less) .

According to the present invention, it is possible to suppress the drop in torque that occurs during startup while keeping the dimensional ratio of the rotor conductor at a constant value without adjusting the dimensions of the rotor conductor according to the material, shape, or power frequency. .

1 is a squirrel cage induction motor and a partially enlarged view thereof as Example 1. FIG. FIG. 2 is a diagram showing an equivalent circuit of a squirrel cage induction motor. It is a figure which shows the coefficient showing the influence of a skin effect. FIG. 6 is a diagram showing the rotational speed (ξ) at which a drop in torque occurs. These are the results of a computer experiment of starting torque. This is a drive system for a squirrel cage induction motor. FIG. 7 is a diagram showing one slot of a rotor of a squirrel-cage induction motor according to a fourth embodiment. FIG. 7 is a diagram showing one slot of a rotor of a squirrel-cage induction motor according to a fifth embodiment. FIG. 7 is a diagram showing one slot of a rotor of a squirrel-cage induction motor according to a sixth embodiment. FIG. 7 is a diagram showing one slot of a rotor of a squirrel-cage induction motor according to a seventh embodiment. FIG. 12 is a diagram showing one slot of a rotor of a squirrel cage induction motor according to an eighth embodiment. FIG. 12 is a diagram showing one slot of a rotor of a squirrel cage induction motor according to a ninth embodiment.

Examples will be described below with reference to the drawings.

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

The stator 1 includes a stator core 2 and a stator winding 4 wound around 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 where the width of the rotor conductor 8 in the circumferential direction X becomes smaller toward the inner circumferential side of the rotor conductor 8. and a second portion 82 that is continuous with the inner circumferential side of the first portion 81 and has a width in the circumferential direction of the rotor conductor 8 that increases toward the inner circumferential side of the rotor conductor 8. The inner circumferential side is the lower side in the right view of FIG.

The rotor conductor 8 including the first part 81 and the second part 82 has a distance h0 from the outer end of the rotor conductor 8 to the inner end of the rotor conductor 8. When the distance from the outer circumferential edge to the outer circumferential edge of the first portion 81 is h1, and the distance from the outer circumferential edge of the rotor conductor 8 to the inner circumferential edge of the second portion 82 is h2. The relationship h1/h0<N<h2/h0 (N is a constant) is satisfied. Here, the constant N is calculated based on the depth of the eddy current penetrating the rotor conductor 8 at a rotation speed at which a drop in torque occurs during startup. Further, the outer circumferential side is the upper side in the right view of FIG.

The rotor conductor 8 is formed by press-fitting aluminum, for example, into the rotor slot 7 by die-casting. Therefore, the rotor conductor 8 has an integral structure within the rotor slot 7 without being divided by parts other than aluminum (for example, slits). However, air bubbles produced during die-casting may also occur in the rotor conductor 8.

In the first embodiment, a double squirrel cage rotor is provided with a first portion 81 and a second portion 82. That is, the rotor conductor 8 includes a third portion 83 on the outer circumferential side of the first portion 81, the third portion 83 having a width in the circumferential direction of the rotor conductor 8 smaller than the outer circumferential end of the first portion 81; The rotor conductor 8 is provided with a fourth portion 84 that is continuous with the outer circumferential side of the portion 83 of No. 3, and the width of the rotor conductor 8 in the circumferential direction increases toward the outer circumferential side of the rotor conductor 8.

FIG. 2 is a diagram showing an equivalent circuit of a squirrel cage induction motor. Using the equivalent circuit of a squirrel-cage induction motor, we derive the relational expression 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 the primary leakage reactance (Ω), x2' is the secondary leakage reactance (Ω), and s is the slip (p.u.).

The secondary input P2(W) is expressed by the following (Formula 1).
P2 = 3 × I2' ² × r2'/ s (Equation 1)

The secondary copper loss W2(W) is expressed by the following (Formula 2).
W2 = 3 × I2' ² × r2' (Formula 2)

The output Pout(W) is the value obtained by subtracting the secondary copper loss from the secondary input, and is expressed by the following (Equation 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 of the output divided by the angular rotational speed ω (rad/sec) of the rotor, and is expressed by the following (Equation 4).
T = Pout / ω
= Pout / (2πN / 60)
= Pout / (2πNs (1 - s) / 60)
= (3 × I2' ² × r2' (1 - s) / s) / (2πNs (1 - s) / 60)
= (3 × I2' ² × r2' / s) / (2πNs / 60)
= (90 × I2' ² × r2' / s) / (πNs)
∝ I2' ² × (r2' / s) (Equation 4)
Where, N: Rotational speed (r/min), Ns: Synchronous speed (r/min)
In the range of slip s where the torque drop is desired to be improved, I2' is approximately inversely proportional to x1+x2'. Therefore, the proportional relationship of torque T is expressed by the following (Equation 5).
T ∝ (r2' / s) / (x1 + x2') ² (Equation 5)

FIG. 3 is a diagram showing coefficients representing the influence of the skin effect. The vertical axis of FIG. 3 shows φ1 in (Equation 8) and φ2 in (Equation 9), which will be described later, which are coefficients representing the influence of the skin effect, and the unit is (p.u.). The horizontal axis in Fig. 3 is ξ (reciprocal ratio of equivalent rotor conductor height), and the unit is (p.u.).

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

r2' = φ1 × r2'dc (Equation 6)
x = x1 + x2'
= φ2 × xdc × K2 + xdc × (1 − K2)
= ((φ2 − 1) K2 + 1) × xdc (Equation 7)
φ1 = ξ(sinh(2ξ) + sin(2ξ)) / (cosh(2ξ) − cos(2ξ)) (Equation 8)
φ2 = 3(sinh(2ξ) - sin(2ξ)) / (cosh(2ξ) - cos(2ξ)) / (2ξ) (Equation 9)
ξ = α × h0 (Equation 10)
α = 2π(10 ^-7 × sf/ρ) ^0.5 (Equation 11)
Here,
φ1, φ2: Coefficients representing the influence of skin effect (pu)
r2'dc: Secondary resistance with zero slip (Ω)
xdc: Leakage reactance with zero slip (Ω)
K2: Ratio of secondary slot leakage to total leakage reactance (pu)
ξ: Reciprocal ratio of equivalent rotor conductor height (pu)
α: Number representing skin depth (1/m)
h0: Rotor conductor height (m)
s: slip (pu)
f: Power frequency (Hz)
ρ: Resistivity of rotor conductor (Ω・m)

The horizontal axis ξ in FIG. 3 is the reciprocal ratio of the rotor conductor height which becomes electromagnetically equivalent when the skin effect is taken into account. As in (Formula 11), when the rotational speed is high (slip s is small), α is small, and as in (Formula 10), when α is small, ξ is small. Similarly, when the rotational speed is low, ξ is large.

That is, the equivalent rotor conductor height decreases as the rotation speed decreases and increases as the rotation speed increases. When the rotational speed is equal to the synchronous speed (slip is 0), α is 0 as shown in (Equation 11), and if α is 0 as shown in (Equation 10), ξ becomes 0. When ξ is 0, coefficients φ1 and φ2 representing the influence of the skin effect are 1, representing a state where there is no influence of the skin effect.

FIG. 3 shows a case where the resistivity ρ of the rotor conductor is uniform within the rotor conductor 8. For example, like the rotor of the squirrel cage induction motor described in Patent Document 1, the rotor However, this does not apply if a plurality of rotor conductors made of materials whose resistance values are sequentially higher from the outer circumference side are provided, or if slits connecting rotor slots are provided.

The rotor conductors 8 are all made of the same material (aluminum) and have an integral structure without being separated by parts other than aluminum (for example, slits) in the rotor slots 7, and the resistivity ρ of the rotor conductors is is uniform within the rotor conductor 8.

FIG. 4 is a diagram showing the rotational speed (ξ) at which the torque decreases. This is the relationship between the power number n(ξ) (vertical axis) and ξ (horizontal axis) when torque T is proportional to the power of ξ. We will derive ξ at the rotational speed where the torque drop occurs.

By substituting (Formula 6) and (Formula 7) into (Formula 5), the proportional relationship of torque T is expressed by the following (Formula 12).
T ∝ (r2' / s) / (x1 + x2') ²
∝ (φ1 / ξ ² ) / ((φ2 − 1) K2 + 1) ² (Equation 12)
When it is assumed that the torque T in (Formula 12) is proportional to the power of ξ, the proportional relationship of the torque T is expressed by the following (Formula 13).
T ∝ ξ ^n(ξ) (Equation 13)
When n(ξ) in (Equation 13) is a positive number, the torque T decreases as the rotational speed increases (a decrease in ξ), and when n(ξ) is a negative number, the torque T decreases as the rotational speed increases (a decrease in ξ). torque T increases accordingly. Therefore, if there is a range in which n(ξ) in (Equation 13) is a positive number, a drop in torque will occur.

As shown in FIG. 4, when the ratio K2 of secondary slot leakage to the total leakage reactance increases, n(ξ) may become positive. That is, as the ratio K2 of secondary slot leakage to the entire leakage reactance increases, a drop in torque tends to occur.

In FIG. 4, when K2 becomes 0.5 or more, n(ξ) may become positive. That is, when K2 becomes 0.5 or more, a drop in torque occurs. When K2 is 0.5, n(ξ) becomes maximum when ξ is 2.2. K2 is at most 1, and when K2 is 1, n(ξ) becomes maximum when ξ is 2.6.

In this way, when K2 is 0.5 to 1.0 and ξ is 2.2 to 2.6, n(ξ) is large (torque decrease is large). In other words, if torque can be increased preferentially at rotational speeds where ξ is 2.2 to 2.6, the drop in torque can be effectively improved.
When the rotor conductor height h0 is 1.0, the skin depth δ is expressed by the following (Equation 14).
δ = 1/(αh0) = 1/ξ (Equation 14)
When K2 is 0.5 to 1.0 and ξ is 2.2 to 2.6, the decrease in torque becomes large, and when ξ is 2.2, the skin depth is 0.45 when ξ is 2.2 in (Equation 14), and similarly When ξ is 2.6, it is 0.38, and when ξ is the average 2.4, it is 0.42.

At a rotational speed at which a drop in torque occurs during startup, the constant N (skin depth δ) calculated based on the depth of eddy current penetrating the rotor conductor is in the range of 0.38 or more and 0.45 or less. As a typical example of this range, a case where the constant N (skin depth δ) is 0.42 will be explained.

As described above, in this embodiment, in order to preferentially increase the torque at a rotational speed where the skin depth δ is 0.42, the process is carried out from the outer circumference side end of the rotor conductor 8 to the inner circumference side end of the rotor conductor 8. By providing a constriction at a position 0.42 times the distance h0 up to the point, r2' is effectively increased to improve the drop in torque.

In this embodiment, by providing a constriction at a position 0.42 times h0, it is possible to improve the drop in torque, and this dimensional ratio is can be left at a constant value without adjustment.

On the other hand, in general, in order to improve the torque characteristics during starting, the radial height and circumferential width of the slits are adjusted according to the material and shape of the rotor conductor and the frequency of the power source, as in Patent Document 1, for example. , it is necessary to adjust the positions appropriately, and as in Patent Document 2, the positions of the first slot and the second slot should be adjusted depending on the material of the rotor conductor and the driving frequency (power frequency). Needs to be adjusted appropriately. From Patent Document 1 and Patent Document 2, even if the material and shape of the rotor conductor and the power frequency are changed, the torque characteristics during starting can be maintained at a constant value without adjusting the dimensional ratio of the rotor conductor. There is no idea in this embodiment that it can be improved.

FIG. 5 shows the results of a computer experiment of starting torque. In the case of this embodiment 1 in Fig. 1, when both h1/h0 and h2/h0 are smaller than 0.42 (when the waist position is shallow toward the outer circumference), and when both h1/h0 and h2/h0 are smaller than 0.42. It shows when the constriction is large (the constriction position is deep toward the inner circumference) and when the constriction is not provided. The target machine has four poles, the rotor conductor 8 is assumed to be aluminum, the resistivity ρ is 3.65×10 ^-8 Ω・m, the rotor conductor height h0 is 51 mm, and the power frequency f is 50 Hz. Torque is rated as 100%.

In this example, the drop in torque has been improved, and the torque is larger on the high rotation speed side than when the constriction position is shallow on the outer circumference side, and the torque is larger on the low rotation speed side than when the constriction position is deep on the inner circumference side. is getting bigger. As a result, in this embodiment, the minimum value of the torque is large both when the constriction position is shallow toward the outer circumference and when the constriction position is deep toward the inner circumference.

Example 2 will be explained. Descriptions of points common to Example 1 will be omitted. Most squirrel cage induction motors are used with rotational speeds ranging from 0 to synchronous speed. The slip s is 1 when the rotational speed is 0, and 0 when the rotational speed is equal to the synchronous speed.

Therefore, the torque drop can also be suppressed by making the slip s at which the torque drop occurs larger than 1, and can be derived as follows.
From (Formula 10), α is expressed by the following (Formula 15).
α = ξ / h0 (Equation 15)
From (Formula 11), the slip s is expressed by the following (Formula 16).
s = ρα ² / (4π ² ×10 ^-7 ×f) (Equation 16)
By substituting (Formula 15) into (Formula 16), the following (Formula 17) is obtained.
s = ρξ ² / (4π ² ×10 ^-7 ×f×h0 ² ) (Equation 17)
When the slip is larger than 1, (Formula 17) is expressed by the following (Formula 18).
1 < ρξ ² / (4π ² ×10 ^-7 ×f×h0 ² ) (Equation 18)
When h0 is derived from (Formula 18), it is expressed by the following (Formula 19).
h0 < ρ ^0.5 ×ξ/ (2π×10 ^-3.5 ×f ^0.5 ) (Equation 19)
ξ at which the torque decreases is between 2.2 and 2.6, and by substituting the average value of 2.4 into (Equation 19), it is expressed by the following (Equation 20).
h0 < 1200(ρ/f) ^0.5 (Equation 20)

Therefore, according to (Equation 20), the torque can be adjusted by adjusting the rotor conductor height h0 according to the resistivity ρ of the rotor conductor 8 in Ω·m and the power supply frequency f in Hz. The slip s at which the drop occurs can be made larger than 1. As a result, a drop in torque can be suppressed.

FIG. 6 is a diagram showing a drive system for a squirrel cage induction motor as a third embodiment. Descriptions of points common to the above embodiments will be omitted.

The squirrel cage induction motor 100 is started by directly supplying commercial voltage and frequency from the power supply 101 to the squirrel cage induction motor 100. Squirrel cage induction motor 100 is mechanically connected to load equipment 102 .

Squirrel-cage induction motors can be started by directly applying commercial power, but the current during starting is about 6 to 10 times the rated current, and the capacity of the power supply equipment is limited to the current at starting. It is determined by the start time. By using the squirrel cage induction motor according to the present invention, a drop in torque is suppressed, the starting time is shortened, and the capacity of power supply equipment can be reduced.

FIG. 7 is a diagram showing one slot of a rotor of a squirrel cage induction motor according to a fourth embodiment. Descriptions of points common to the above embodiments will be omitted.

The positions of the first portion 81 and the second portion 82 of the rotor conductor 8 are determined by the boundary position of the first portion 81 and the second portion 82 (the circumferential width of the first portion 81 and the second portion 82). It is not necessarily necessary that the position where the minimum is 0.42 times the rotor conductor height h0. For example, as shown in FIG. 7(a), even if there is a position where the second part 82 has a multiplier of 0.42, the first part 81 has a multiplier of 0.42, as shown in FIG. 7(b). There may be a position.

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

FIG. 8 is a diagram showing one slot of a rotor of a squirrel cage induction motor according to a fifth embodiment. Descriptions of points common to the above embodiments will be omitted.

The rotor conductor 8 has a section between the inner end of the first section 81 and the outer end of the second section 82, the width of which is constant in the circumferential direction. Since the section with a small width in the circumferential direction becomes larger, the effect of suppressing a drop in torque increases.

FIG. 9 is a diagram showing one slot of a rotor of a squirrel cage induction motor according to a sixth embodiment. Descriptions of points common to the above embodiments will be omitted.

At the outer peripheral end of the first portion 81 and the inner peripheral end of the second portion 82, the rotor conductor 8 has a circumferential width that changes stepwise. Compared to a gradual change, since the area with a small width in the circumferential direction becomes larger, the effect of suppressing a drop in torque is enhanced.

FIG. 10 is a diagram showing one slot of a rotor of a squirrel cage induction motor according to a seventh embodiment. Descriptions of points common to the above embodiments will be omitted.

A seventh embodiment will be described using a convex rotor, which is an example of a rotor of a squirrel cage induction motor. In Example 7, the convex rotor is provided with a first portion 81 and a second portion 82. That is, the rotor conductor 8 includes a third portion 83 on the outer circumferential side of the first portion 81, the width of the rotor conductor 8 in the circumferential direction is smaller than the outer circumferential end of the first portion 81. .

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

By reducing the circumferential width of the rotor conductor 8, the current when the slip is large is reduced. The effect of reducing the circumferential width of the rotor conductor 8 is greater as the outer circumference of the rotor conductor 8 increases. By providing the second portion 82, the current when the slip is large is reduced.

FIG. 11 is a diagram showing one slot of a rotor of a squirrel cage induction motor according to an eighth embodiment. Descriptions of points common to the above embodiments will be omitted.

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

By reducing the circumferential width of the rotor conductor 8, the current when the slip is large is reduced. The effect of reducing the circumferential width of the rotor conductor 8 is greater as the outer circumference of the rotor conductor 8 increases. By providing the portion 82, the current when the slip is large is reduced.

FIG. 12 is a diagram showing one slot of a rotor of a squirrel cage induction motor according to a ninth embodiment. Descriptions of points common to the above embodiments will be omitted.

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

The circumferential width of the sixth portion 86 at the outer circumferential end is larger than the circumferential width at the outer circumferential end of the first portion 81 .

When the width of the rotor conductor 8 in the circumferential direction is reduced, the power factor during steady operation with small slip is reduced. The first portion 81 and the second portion 82 are provided in an eggplant-shaped rotor in which the circumferential width of the rotor conductor 8 is smaller than that of a double squirrel-cage rotor, a convex rotor, or a diamond-shaped rotor. This improves the power factor when the slip is small.

Although embodiments have been described above, the present invention is not limited to the embodiments described above, and includes various modifications. For example, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is also possible to add, delete, or replace a part of the configuration of each embodiment with other configurations.

DESCRIPTION OF SYMBOLS 1...Stator, 2...Stator core, 3...Stator slot, 4...Stator winding, 5...Rotor, 6...Rotor core, 7...Rotor slot, 8...Rotor conductor, 9...Shaft , 10... Gap, 100... Squirrel cage induction motor, 101... Power supply, 102... Load equipment

Claims (10)

A rotor having a rotor conductor,
The rotor conductor is
a first portion where the width of the rotor conductor in the circumferential direction becomes smaller toward the inner circumferential side of the rotor conductor;
a second portion that is continuous with the inner circumferential side of the first portion and the width of the rotor conductor in the circumferential direction increases toward the inner circumferential side of the rotor conductor;
The distance from the outer peripheral end of the rotor conductor to the inner peripheral end of the rotor conductor is h0,
The distance from the outer circumferential end of the rotor conductor to the outer circumferential end of the first portion is h1,
The distance from the outer peripheral end of the rotor conductor to the inner peripheral end of the second portion is h2,
The rotor conductor is
A rotor that satisfies the relationship h1/h0<N<h2/h0 (N is a constant of 0.38 or more and 0.45 or less) . The rotor according to claim 1,
The rotor conductor is
between the inner peripheral end of the first part and the outer peripheral end of the second part,
A rotor that has a section with a constant width in the circumferential direction. The rotor according to claim 1,
The rotor conductor is
At the outer peripheral end of the first part and the inner peripheral end of the second part,
A rotor whose circumferential width changes stepwise. The rotor according to claim 1,
The rotor conductor is
a third portion on the outer peripheral side of the first portion, the width of the rotor conductor in the circumferential direction being smaller than the outer peripheral end of the first portion;
and a seventh portion connected to the inner circumferential side of the third portion, the width of the rotor conductor in the circumferential direction increasing toward the inner circumferential side of the rotor conductor. The rotor according to claim 1,
The rotor conductor is
A fifth portion is provided on the outer circumferential side of the first portion, and the circumferential width of the rotor conductor gradually decreases toward the outer circumferential side;
The circumferential width at the outer circumferential end of the fifth portion is:
The rotor has a circumferential width smaller than the circumferential width at the outer circumferential end of the first portion. The rotor according to claim 1,
The rotor conductor is
A sixth portion is provided on the outer circumferential side of the first portion, and the circumferential width of the rotor conductor gradually increases toward the outer circumferential side;
In the rotor, the circumferential width at the outer circumference side end of the sixth section is larger than the circumferential width at the outer circumference side end of the first section. The rotor according to claim 1,
When the resistivity of the rotor conductor is expressed in Ω·m as ρ, and the power supply frequency is expressed in Hz as f,
The h0 is
A rotor that satisfies the relationship h0<1200(ρ/f)0.5. The rotor according to claim 1,
Has a rotor core,
The rotor conductor is
disposed in a rotor slot formed in the rotor core,
A rotor having a shaft on the inner peripheral side of the rotor core. A squirrel cage induction motor comprising the rotor according to claim 1. A drive system comprising the squirrel cage induction motor according to claim 9 , a power source, and load equipment.

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