JPH0471363A - Superconducting generator field-winding - Google Patents

Abstract

PURPOSE:To reduce a concentrated magnetic field without increasing the end section length of a rotor by arranging coils inserted into each slot by stages so that the end-section axial direction intervals of the coils are increased relatively in the coils nearer to a magnetic pole and reduced relatively in the coils further from the magnetic pole. CONSTITUTION:In a superconducting field-winding, a section between coils nearest to a magnetic pole is brought to 1.20Xl/(n-1) or more on n(where n>=4) coils and end-section length of (l), a section between the next coils to 1.05Xl/(n-1) or more, and they are reduced by stages, and a section between coils furthest from the magnetic pole is brought to 0.80Xl/(n-1) or less, a section between the coils far from the magnetic pole next to 0.95Xl(n-1) or less, and the sum total among all coils is brought to (l) in the end-section axial direction intervals of the coils in arrangement of the coils. Consequently, the magnetic flux concentration of the coil nearest to the magnetic pole is relaxed, and the magnetic flux concentration of the coil furthest from the magnetic pole is increased. Accordingly, the maximum magnetic flux concentration of each coil is levelled, and maximum magnetic flux density as the whole field- winding is minimized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a superconducting field winding of a superconducting generator, and particularly to a superconducting field winding that is divided into a plurality of slots cut into a rotor of a superconducting generator. This relates to the relaxation of magnetic flux concentration at the end of the field winding of the type that is housed.

[Conventional technology]

The spacing of conventional superconducting field windings in the rotational axis direction is disclosed in Japanese Unexamined Patent Publication No. 5
As shown in FIG. 4 of Publication No. 8-50093, they are arranged at equal intervals. A known method for reducing magnetic flux concentration at the ends is to reduce the size of the magnetic poles near the magnetic poles.

Another method is to change the current density instead of changing the shape. However, the end axial spacing in both of the above two methods remains equally spaced. In order to further reduce the concentration of magnetic flux by arranging the coils at equal intervals, it is conceivable to increase the length of the end portions in the direction of the rotational axis to some extent or to increase the spacing so that the mutual influence between the coils is reduced.

Another method is to greatly expand the radius of the saddle at the end to reduce magnetic flux concentration, as seen in the two-pole magnetic coil of a particle accelerator, but when applied to a generator, the rotor It cannot be used because of the restriction that the outer diameter is constant.

[Problems to be Solved by the Invention] When designing the shape of a superconducting field winding, there are certain limitations. That is, when the rated capacity is determined, the required magnetic field, the radius of the coil that effectively generates the magnetic field, and the linear length of the coil are determined to some extent. Furthermore, in order to efficiently utilize the magnetic flux generated by the rotor, the length of the stator and the end length of the rotor are determined to a certain extent.

Due to the above limitations, it is not preferable to increase the axial distance between the coils in order to alleviate magnetic flux concentration at the end of the rotor. There is also the problem of vibration, which is a bigger factor. If the rotor becomes longer in the axial direction, the critical speed of the rotor will decrease, which is undesirable in terms of rotor vibration, so the shorter the rotor, the better.

Conventional technology does not take into consideration the above points,
There were problems with implementation.

- An object of the present invention is to provide a superconducting generator field winding that reduces the concentrated magnetic field without increasing the end length of the rotor.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a superconducting field winding that is used by cutting a plurality of slots in the field winding attachment shaft of the rotor of a superconducting generator, and inserting and fixing the field winding into each slot. The axial distance between the ends of the coils inserted into each slot is relatively large for the coils close to the magnetic poles;
The superconducting field winding is characterized in that it is arranged in stages so that the coils farther from the magnetic pole are relatively smaller.

In the superconducting field winding, if there are η coils (n≧4) and the end length is l, the distance between the coils closest to the magnetic poles is 1.20×I.
l/(n-1) or more, and 1.05 between the next coils.
The distance between the coils farthest from the magnetic pole is 0.80×4! /(n-4>
Below, the distance between the next farthest coils is 0.95 × l/ (n
-1) It is preferable to use the following and to adopt an arrangement in which the sum of all the coils is a sum.

In addition, in the above, when n is 4 to 8, in particular, the end axis direction of the coil is 1.20 between the coils closest to the magnetic poles.
~1.25xj! / (n-1), the distance between the next coils is 1.05~L10Xff/(nl), the distance between the coils farthest from the magnetic pole is 0.75~0,80 between 0.90 and 0.95xβ/ (T
I-1), and it is preferable to adopt an arrangement in which the sum of all the coils is 1.

In addition, in a normal field winding, the distance in the axial direction of the coil ends is ! if there are n coils and the end length is l. /(n
-1).

That is, in the present invention, in order to reduce the influence of other coils, especially the second coil, on the coil closest to the magnetic pole where the magnetic flux is usually concentrated the most, the distance between the coil closest to the magnetic pole and the second coil is set at equal intervals. The second and third coils are spaced relatively apart from each other, and the distance between the second and third coils is also spaced apart from each other, although not as much as the first coil. On the other hand, the spacing between coils far from the magnetic poles is made relatively small.

By adopting the above configuration, the magnetic flux that is normally concentrated in the coil closest to the magnetic pole can be relaxed and the maximum magnetic flux density can be reduced.

[Effect]

Superconducting generator (two-pole machine) with a superconducting field winding in the rotor
Let us consider the case of . When using superconducting wire,
The biggest difference from normal conductive wire is that due to the tl-1c characteristic of superconductivity, as the magnetic field increases, the current that can be passed decreases.

Therefore, making the value of magnetic field concentration as small as possible is an important issue for superconducting field windings. Among the methods proposed to reduce the value of magnetic flux concentration, the common method is to keep the current density constant, change the shape of the slot, and set the magnetic flux distribution to an ideal CO8θ arrangement.
A method has also been proposed in which the shape of the slot is kept constant and the current density is varied. Both of the above two cases are methods of reducing magnetic flux concentration at the ends by improving the straight portion, and the ends of the coil are arranged at equal intervals.

Usually, the coil in which the magnetic flux concentrates the most is the coil closest to the magnetic pole. This is because all other coils affect the coil closest to the magnetic pole. Next, the second coil has less magnetic flux concentration than the first coil because the first coil functions to alleviate the magnetic flux concentration. Therefore, when there are a plurality of coils, the magnetic flux is most concentrated in the coil closest to the magnetic pole, and the value of the magnetic flux concentration decreases as the coil moves away from the magnetic pole.

In the present invention, the value of the magnetic flux concentration of the coil closest to the magnetic pole is reduced by relatively increasing the axial distance between the ends of the coil closest to the magnetic pole and the second coil, and gradually decreasing the spacing between the ends of the coil closest to the magnetic pole. On the contrary, the value of magnetic flux concentration of the coil which is small and far from the magnetic pole can be increased. Therefore, the value of magnetic flux concentration of each coil can be averaged, and the maximum value of magnetic flux can be reduced.

〔Example〕

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Example 1 An example of the present invention will be explained with reference to FIG. In Figure 1,
The end axial spacing between the coil closest to the magnetic pole and the second coil is about 25% larger than the equal spacing shown in FIG. The second and third coil spacing is 5% larger than the equal spacing case. On the other hand, the spacing between the third and fourth coils is 8
%, the spacing between the 4th and 5th coils is 22%, which is conversely smaller than the case of equal spacing.

By adopting the above configuration, the magnetic flux concentration in the coil closest to the magnetic pole is relaxed, and the magnetic flux concentration in the farthest coil is increased. Therefore, the maximum magnetic flux concentration of each coil is averaged,
The maximum magnetic flux density of the field winding as a whole decreases.

The magnetic field distribution in the case of adopting the configuration of the present invention and in the case of adopting the equally spaced configuration was calculated and studied using a three-dimensional magnetic field analysis code. The results are shown in Figure 3.

FIG. 3 is a magnetic field distribution diagram where the vertical axis represents the maximum magnetic flux density in each coil of the present invention and the conventional winding, and the horizontal axis represents the distance from the center to each coil.

In the case of the present invention, the specifications of the winding for which this magnetic field analysis was performed are
FIG. 5 shows a conventional example of equal spacing.

In Figures 4 and 5, 1 is the length of the conductor end, which is 320
mm, 2 is 1200mm at the conductor straight section.

3 is the radius, 320111 [0,4 is the conductor cross section, 5
is the conductor thickness of 24mm, 6 is the conductor width of 76+n+++,
7 represents a conductor with 5 pieces/pole, and the central magnetic field is 3 Tesla.

As can be seen from FIG. 3, in the case of equidistant arrangement, the magnetic flux is most concentrated in the coil closest to the magnetic pole, and a magnetic field of approximately 4 Tesla is generated. On the other hand, according to the arrangement of the present invention, the magnetic field of each coil is averaged between 3.6 Tesla and 3.7 Tesla, and the maximum magnetic flux density is 3.7 Tesla.

Therefore, according to this embodiment, under the conditions of the limited outer diameter and length of the field winding, the end magnetic flux concentration can be reduced by 7.5% compared to the case where the field windings are arranged at equal intervals. The above is an example of the case of five coils, but the same thing can be said when the number n of coils is four or more.

As a result of calculations for the case where n is 4 to 8, the most important points for alleviating magnetic flux concentration are the coil closest to the magnetic pole and the
The goal is to space the coils as far apart as possible. however,
If the magnetic fields are separated too far, concentration in other coils will become significant, which is undesirable. Ideally, the magnetic field should be distributed evenly. To do this, the distance between the coils closest to the magnetic poles is about 20 to 25% compared to the case where they are equally spaced, and the distance between the next coils is 5 to 10%. Conversely, between the coils far from the magnetic pole, 2
It can be made relatively ideal by narrowing it by about 0 to 25% and then narrowing the farthest coil by 5 to 10%. Moreover, almost the same results are obtained when n is 9 or more.

〔Effect of the invention〕

According to the present invention, magnetic flux concentration at the end of the saddle-type superconducting field winding attached to the rotor of a superconducting generator can be reduced under the conditions of the limited radius and length of the field winding.

Therefore, when using the same superconducting wire as when this configuration is not adopted, the margin up to the critical magnetic field increases, so there is an effect that the generated magnetic field can be increased.

Further, when the generated magnetic field is the same, if this configuration is adopted, the margin up to the critical magnetic field increases. This margin is used to shorten the length in the axial direction of the end portion. In other words, by adopting this configuration, it is possible to offset the magnetic flux concentration at the end, which increases by shortening the length in the axial direction of the end. Therefore, by adopting this configuration, the length of the field winding can be shortened. Since vibration can be reduced, safety and stability are improved.

[Brief explanation of drawings]

Fig. 1-a is a bird's-eye view of a field winding with unevenly spaced ends according to an example of the present invention, Fig. 1-b is a sectional view of Fig. 1-a viewed from the X-axis, and Fig. 1-b is a cross-sectional view of Fig. 1-a viewed from the Figure a is a cross-sectional view of Figure 1a viewed from the y axis (however, 1/2, 1/2 in the x, y, and z directions).
1/4 of the pole coil is shown. ) Figure 2-a is a bird's-eye view of a conventional field winding with equally spaced ends in the axial direction, and Figure 2-b is a diagram of
A cross-sectional view of Fig. 2-a viewed from the y-axis direction, Fig. 2-a is
Fig. 2-a is a cross-sectional view when viewed from the X-axis direction, and Fig. 3 shows the distance from the center to each coil, with the vertical axis representing the maximum magnetic flux density in each coil of the present invention and the conventional winding. Fig. 4 is a cross-sectional view showing the specifications of windings arranged at uneven intervals for which magnetic field analysis was performed, and Fig. 5 is a diagram of the windings arranged at equal intervals for which magnetic field analysis was performed. It is a sectional view showing specifications of a line. 1... Conductor end, 2... Conductor straight part, 3... Radius, 4
...Conductor cross section, 5...Conductor thickness, 6...Conductor width,
7...Conductor patent applicant Hiroshi Nakamoto, Representative of Superconducting Power Generation Related Equipment and Materials Technology Research Association
Inoue Sho 141!1

Claims (1)

[Claims] 1. In a superconducting field winding that is used by cutting a plurality of slots in the field winding attachment shaft of a rotor of a superconducting generator and inserting and fixing it into each slot, A superconducting field winding characterized in that the distance between the ends of the inserted coils in the axial direction is arranged in stages so that the distance in the axial direction between the ends of the coils is relatively large in the coils close to the magnetic poles and relatively small in the coils far from the magnetic poles. line. 2. In the superconducting field winding, if there are n coils (n≧4) and the end length is l, the distance between the coils closest to the magnetic poles is 1.20 x l. /(
n-1) or more, and the distance between the next coils is 1.05×l/(n
-1) or more, and then gradually decrease the value so that the distance between the coils furthest from the magnetic pole is 0.80×l/(n-1) or less, and the distance between the next farthest coils is 0.95×l/(n-1). ) below,
The superconducting field winding according to claim 1, characterized in that the superconducting field winding is arranged so that the sum of all the coils is l. 3. In the superconducting field winding, if there are n coils (n = 4 to 8) and the end length is l, the distance between the coils closest to the magnetic poles is 1.20. ~1
．． 25×l/(n-1), and the distance between the next coils is 1.05
~1.10×l/(n-1), the distance between the coils furthest from the magnetic pole is 0.75-0.80×l/(n-1), and the distance between the next furthest coils is 0.90-0. 95×l/(n-1)
3. The superconducting field winding according to claim 2, wherein the superconducting field winding is arranged so that the sum of all the coils is l.