JPS59198868A - Rotor of superconductive rotary electric machine - Google Patents

Abstract

PURPOSE:To average the margin of designing a field winding to a magnetic field by increasing a conductor sectional area for forming the turn of a coil of the strong portion of a magnetic field of a superconductive field winding larger than that for forming the turn of the other. CONSTITUTION:A rotor of a superconductive rotary electric machine is formed by forming a central chamber 5 for accumulating liquid helium in the bore side of a shaft 2 and winding a superconductive field winding 1 on a pair of poles 3 of the outer periphery. At this time, the winding 1 is wound as a conductor with two strands 9 in parallel at the coil 1a near the poles, and as a conductor with one strand 9 of the same sectional area as the strand 9 of the coil 1a at the other coil 1b. Accordingly, the sectional area of the conductor near the pole of the strongest magnetic field is increased, the current density of the portion is reduced to average the margin of the entire field winding, thereby providing the safety and high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rotor for a superconducting rotating electric machine in which a superconducting field winding of the rotor is improved.

[Technical background of the invention and its problems]

The rotor of a superconducting rotating electrical machine uses superconducting wire for its field winding, and is kept at an extremely low temperature with liquid helium or the like. This is because the electrical resistance of the field winding is eliminated and a large current can be passed without loss, resulting in a strong magnetic field. Therefore, since it has the advantage of being a high-output rotating electrical machine with little loss, research and development thereof has been rapidly progressing in recent years.

However, this superconducting wire has a certain value ■ of current flowing through the superconducting wire. or when the temperature of the superconducting wire exceeds a certain value T. or when the magnetic field applied to the superconducting wire exceeds a certain value H6, the superconducting state returns to the normal conducting state where resistance exists in either case. ■ Critical current for each value. , critical temperature Tc, and critical magnetic field Hc.

This ■. , Tc, and HoK each have a close relationship,
For example, with Tc as a parameter, the temperatures T, , T
,,T.

IC and H when TI < T2 < T3 for
The characteristic diagram of No. 6 is shown in FIG. 1. As is clear from Fig. 1, if the temperature is constant, the larger Hc is, the lower the temperature will be.

If HC becomes smaller and HC becomes smaller, IC becomes larger. In FIG. 1, a superconducting state is established on the lower left side of the temperature curve, and a normal conducting state is established on the upper right side.

When multiple coils are made from superconducting wire and these coils are arranged concentrically and connected in series to form a superconducting field winding, most of the magnetic circuits in the superconducting rotating electric machine have a magnetic permeability of μ2. 1, so if the current flowing through the superconducting field winding is determined, the magnetic field generated by that coil at a certain location is determined, and the magnitude of the current and magnetic field are directly proportional.

Next, the field winding (1) in which each coil cross section is continuous in the circumferential direction as shown in Fig. 2 is attached to the magnetic pole part (3) of the shaft part (2).
Consider the case where two sets are arranged facing each other on both sides.

In this case, for example, as is clear from Figure 3, the magnetic flux density component in the radial direction on line ABCD when the inner diameter part of the coil is viewed in the circumferential direction, the location where the magnetic flux density component is largest is the magnetic pole part (3).
It turns out that it is a nearby coil.

This relationship holds true even where the radius is a little larger than the inner diameter line of the coil.

Therefore, if the point near the magnetic pole part (3) of the coil (in this explanation, on the inner diameter side of the coil) is Q, and the point that can be reached to some extent from the vicinity of the magnetic pole part (3) is P, then the magnetic flux density at points Q and P is is determined by the current in the field coil, and when the relationship between this current and the magnetic field is plotted on FIG. 1, it is represented by a straight line and a phase, respectively. From this Figure 1, the rated current ■ for each coil in the field winding (1). When is flowing, it can be seen that magnetic fields HP and HQ are generated at point P and point Q, respectively. And if the temperature is constant at T, then increasing the current causes P
It can be seen that from point KQ to point KQ, the current of IQ reaches the boundary shown by the characteristic curve of T, and cannot flow any further. In short, P
At the point, it is possible to flow up to IP, but at point Q, it is only possible to flow up to IQ, so it can be seen that there are restrictions at this point. or,
If the current is constant and the temperature changes, the P point remains superconducting up to 13 degrees, but the Q point will break down at a low temperature of 12 degrees.

Similar to the case described above, when the temperature is T1 and the current is constant, the Q point has much less margin for the critical magnetic field HR that causes normal conductivity.

Furthermore, when designing the superconducting field winding of the rotor of a superconducting rotating electrical machine, it is important to note that during the operation of the rotating electrical machine, the superconducting wire may undergo a transition to normal conductivity due to the influence of an external fluctuating magnetic field due to a short circuit in the armature winding. In order to prevent this, the design must allow sufficient margin for the magnetic field, current, and temperature during operation. In this case, as mentioned above, the current and temperature are almost uniform throughout the field winding, so
The design has the same amount of margin everywhere in the field winding, but the margin for the magnetic field varies depending on the location occupied by each coil in the field winding. The magnetic flux at the point is maximum and the margin is minimum.

Therefore, when designing the field winding, it is necessary to take into consideration a margin of an appropriate ratio to the maximum magnetic flux near the magnetic pole portion (3).

However, as shown in Figure 3, the maximum magnetic flux near the magnetic pole is only in a small part of the field, and in most other parts of the field winding, the magnetic flux level is even lower. , there is a lot of leeway.

In other words, the design level of the rotor field winding of a conventional superconducting rotating electrical machine is limited by the high magnetic flux generated in a small portion near the magnetic poles, and the design level is limited for most other parts of the field winding. It had to become inefficient with a very large amount of leeway.

[Purpose of the invention]

An object of the present invention is to provide a rotor for a superconducting rotating electrical machine that is safer and more efficient overall by equalizing the design margins of field windings with respect to the magnetic field.

[Summary of the invention]

In the present invention, in a rotor having a superconducting field winding, among the conductors of each turn of the coil located near the magnetic pole part of the field winding, at least the cross-sectional area of the conductor of the turn on the inner diameter side is By making the cross-sectional area of the conductor of the turn of the coil larger than that of the turn of the other coils, the current density of the conductor of the turns of the coil in the part where the magnetic field is strong is made smaller, the safety factor against the magnetic field is made uniform, and the field winding is made larger. It increases the efficiency of

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 4 to 6. FIG. 4 shows a cross-sectional view of the center of a rotor having superconducting field windings according to this embodiment. However, the fifth
The figure shows only the structures near the field winding that are important in this embodiment. On the inner diameter side of the rotor shaft (2) there is a central chamber (5) in which liquid helium (4) is stored. shaft(
A pair of magnetic pole parts (3) and (3) are formed on the outer periphery of the magnetic pole part 2), and slot parts (6) and (6) are formed. Inside the slot portion (6) is a coil (1a) located near the magnetic pole portion.
) and another central coil (1b) are arranged concentrically. Each coil (la),
, (lb) and between the magnetic pole part (3) and the adjacent coil (la?) in the circumferential direction, a spacer (7) made of an insulator with a wedge-shaped cross section extending in the axial direction is arranged. This coil (1, a), (lb) spacer (7)
At the outer periphery of are their centrifugal forces and coils (la).

There is an ind ring (8) for fixing against the electromagnetic force of (lb).

FIG. 5 shows a sectional view of the coil (1a) or (1b).

The coils (la) and (lb) are made by winding a superconducting wire (9) as a conductor many times. In the coil (1a) near the magnetic pole, two wires (9) are wound in parallel to form a single conductor, and in the other coils (1b), the wires (9) are wound in parallel to form a single conductor. One wire (9) having the same cross-sectional area as (9) is wound as one conductor.

The coils (la) and (lb) are connected in series to form a field winding (1). The connection portion between one conductor of element a (9) and two conductors of element wire (9) is connected by a pinching method as shown in FIG. In this case, one coil (1a
) or (1b), the number of strands (9) is an even number, so the coil (1a) near the magnetic pole part is similar to the other coil (1a).
The number of turns is only half that of b), but the cross-sectional area is the same.

Next, the effect will be explained.

The field winding (1) of this embodiment is similar to that shown in FIG.
Figure 7 shows a straight line showing the relationship between the magnetic field and current of the superconducting wire in , and a characteristic diagram when the temperature changes.

In Fig. 7, the temperatures of the superconducting wire 'r, l'r, .
The characteristics at 'r are the same as those in the conventional FIG. 1, and the relationship OP between the magnetic field and current of the central coil (1b) shows a value almost similar to OP in FIG. However, at point Q on the inner diameter side of the coil (1a) near the magnetic pole part where the magnetic field is highest in Figure 1, the cross-sectional area of the conductor is twice as large, so the current value is half of the force corresponding to the plane in Figure 1. The relationship is Q. Therefore, when the field winding (1) of this embodiment is operated at the rated current □, the center coil (1b) maintains the same temperature T3 as the PR point in Fig. 7. , the coil (1a) near the magnetic pole part is allowed to have a magnetic field at point QR with respect to 1/2 of the current, that is, R/2. In this case, the permissible current value that can be safely passed is very large, whereas the conventional field winding could only allow current up to IQ to flow up to twice IQ or the value of IP, whichever is smaller. becomes larger.

In addition, when the current is constant and the temperature changes, conventional field windings could only tolerate temperatures up to 11 degrees, but with the field winding of this example, it can be safely used up to a higher temperature of 13 degrees. I see that it is possible. Temperature and current power! The margin when the magnetic field is constant and changes is not determined by the HR/HQ ratio as in the past, but by HR/HQ.
Since the ratio is HP or (a value greater than or equal to HR)/HQ, the safety factor becomes high.

If the current value is increased so that the safety factors for temperature, current, and magnetic field in this embodiment are at the conventional level, a highly efficient rotor with a large output magnetic field can be obtained with field windings having the same shape.

The present invention is not particularly limited to the structure of the above-mentioned embodiment, but in other words, the present invention is not limited to the structure of the above-mentioned embodiment, but in other words, among the entire coils (la) and (lb) constituting the field winding (1), the parts where the magnetic field is particularly high are The key point is to locally lower the current density of the superconducting wire. Therefore, for example, the coil (1a) near the magnetic pole part
In this case, the magnetic field is especially high on the inner side of the coil, so only the conductors of the four turns on the inner side of the coil shown in Figure 5 are made of two strands in parallel, and the rest are made of one strand of wire. You may also use In this case, there is an advantage that the total number of turns in the field winding a(1) is greater than in the previously shown embodiment.

Alternatively, a coil in which turns are formed using thick wires using wires having different cross-sectional areas may be used as the coil (1a) near the magnetic pole portion.

〔Effect of the invention〕

As explained above, according to the present invention, the cross-sectional area of the conductor forming the coil turn in the part of the superconducting field winding where the magnetic field is strong is made larger than the cross-sectional area of the conductor forming the other turns. The current density in the parts becomes smaller, and the margins in the design of each part of the field winding are averaged, making it possible to provide a rotor of a superconducting rotating electric machine that is safer and more efficient as a whole.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between magnetic field, current, and temperature in the superconducting wire of the field winding of the rotor of a conventional superconducting rotating electrical machine. Figure 2 is a cross-sectional conceptual diagram of the rotor in Figure 1. Figure 3 is the second
Figure 4 is a distribution diagram of radial magnetic flux density on the inner diameter surface of the field winding of the rotor, Figure 4 is a helical cross-sectional view, Figure 5 is an enlarged cross-sectional view showing the coil in Figure 4, and Figure 6 is a cross-sectional view of the coil in Figure 4. FIG. 5 is a longitudinal cross-sectional view showing the conductor connection portion, and FIG. 7 is a characteristic diagram showing the relationship between the magnetic field, current, and temperature in the superconducting wire of the field winding of the rotor shown in FIG. 4. ■... Field winding 1a... Coil 1b near the magnetic pole part... Other coils 3... Magnetic pole part 9... Element wire forming the conductor 10... Inner diameter side agent Patent attorney
Inoue - Male Figure 1 Figure 48 Figure 5

Claims (3)

[Claims] (1) In a rotor having a superconducting field winding, among the conductors of each turn of the coil located near the magnetic pole part of the field winding, at least the cross-sectional area of the conductor of the turn on the inner diameter side is and a rotor for a superconducting rotating electric machine characterized by fi: having a cross-sectional area larger than the cross-sectional area of the conductor of the turns of the other coils. (2) The conductor having a large cross-sectional area is formed by connecting two wires in parallel having the same cross-sectional area as the wire forming the conductor having a small cross-sectional area. Rotor of superconducting rotating electric machine. (3) The superconducting rotating electrical machine according to claim 1, characterized in that the conductor with a large cross-sectional area uses a wire with a cross-sectional area υ larger than the wire forming the conductor with a small cross-sectional area. rotor.