JPS5822940B2 - Kaiten Denki - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a rotating electrical machine using a superconducting field winding, and in particular a rotating electric machine using a superconducting field winding that can operate efficiently as an AC motor in both synchronous and asynchronous modes. It is related to rotating electric machines.

Over the past 10 or 12 years, much attention has been paid to the use of the extremely low electrical resistance state that certain materials exhibit at cryogenic temperatures, known as superconductivity, in rotating electrical machines.

Because extremely strong magnetic fields can be obtained by exploiting the superconducting effect, prior art efforts in the field of superconducting machines have been directed toward utilizing essentially all-gap structures in which no ferromagnetic material is used.

Through these efforts, a rotating electric machine that operates properly as a synchronous AC motor has been created.

However, these machines do not operate effectively during asynchronous operating regimes such as those encountered during start-up or when there are transient conditions.

One of the problems when full air gap configurations are used in AC motors is that the torque produced during asynchronous operation is relatively small.

This is because during starting, the electric machine operates as an induction motor with an alternating magnetic field that is as strong as before and sometimes even smaller.

Since the magnetic field is only a fraction of the magnetic flux produced by the superconducting windings, the lack of ferromagnetic paths results in very inefficient use of this relatively small amount of magnetic flux.

Therefore, the torque produced during this mode of operation is extremely small.

Another problem that arises during asynchronous operation of superconducting AC motors is that relatively low frequency alternating magnetic fields penetrate into the superconducting windings, such as when there is a slight deviation from the synchronous speed.

Since superconductivity is essentially a direct current phenomenon, the introduction of an alternating magnetic field results in relatively high energy losses, which is unacceptable.

Losses are not undesirable; they can result in "quenching" or loss of superconducting effect.

Therefore, in prior art devices, U.S. Patent No. 3,679,92
A separate magnetic flux shield as described in No. 0 shall be included.

A rotating electrical machine that overcame these difficulties was patented in 1984.
No. 557 (Japanese Unexamined Patent Publication No. 49-105101), this application provides a rotating electrical machine using a superconducting field winding that operates well as an AC motor in both synchronous and asynchronous states. ing.

However, this machine has drawbacks with respect to undesirable magnetic flux losses during synchronous operation and cooling arrangements.

The rotating electrical machine of the present invention is an improvement on the rotating electrical machine of the above-mentioned application, and eliminates the disadvantages of the rotating electrical machine without losing its advantages.

The rotating electric machine of the invention includes an armature having a suitable armature winding thereon.

In certain embodiments, the armature is a generally cylindrical stationary ring with an armature winding disposed in a slot along its inner circumference.

The field device is mounted inside the armature ring and is arranged to move relative to the armature.

The field device electrical conductors are located close to the armature winding and separated from it by an air gap.

When a rotating electric machine is used as an AC motor, the conductor is
It is arranged to respond to the alternating magnetic flux produced by the armature winding during a starting operation.

Therefore, during starting, the rotating electrical machine essentially operates as an induction motor, and the electrical conductors can be either bars of the squirrel cage winding or bars of the rotor winding.

In the particular embodiment described herein, the electrical conductor is placed along the outer periphery of a first core of ferromagnetic material.

A first portion of ferromagnetic material within the first core is arranged to provide a plurality of magnetic poles.

A superconducting winding is wound around the first portion to provide magnetic flux to the magnetic pole.

The superconducting winding may be either monofilament or multifilament, and has separate segments wound around appropriate portions of the ferromagnetic material.

The superconducting winding is insulated from both the magnetic poles and the surrounding conditions by an insulating structure such as a dewar.

The superconducting winding is spaced apart from the electrical conductor such that a second portion of ferromagnetic material within the first core separates the superconducting winding from the electrical conductor.

These second portions are integral parts of the first core and provide a magnetic flux path between a pair of adjacent magnetic poles.

During the startup period of a rotating electric machine, when it operates as an AC motor, the superconducting windings may or may not be superconducting, but the superconducting windings are started with no current flowing through them, and these The two parts form a shunt for the relatively low frequency alternating magnetic flux and prevent it from penetrating into the superconducting windings.

Therefore, the Joule loss caused by low frequency magnetic flux in the cryogenic part is small, and the superconducting state is maintained.

However, during synchronous operation these second portions of ferromagnetic material are saturated and the flux shunted through them is only a relatively small portion of the total flux generated by the superconducting windings.

The third portion of ferromagnetic material includes segments of the first core extending toward each other from adjacent magnetic poles.

Non-ferromagnetic areas, such as air gaps, are located between the ends of the spaced segments.

During asynchronous operation of the rotating electric machine, the air gap between the segments prevents the magnetic flux from passing through, so the magnetic flux passes through the path formed by the second portion of ferromagnetic material.

When the second part saturates during synchronous operation, the main magnetic flux returns to the path through the extending segment.

It may include a main flux path or ferromagnetic section (contained within the third portion) that is separated from the segments in the pole by a non-ferromagnetic area such as an air gap.

These sections are provided by a second generally cylindrical annulus of ferromagnetic material forming a second core.

If the segments are omitted or the air gap between them is large enough, these sections can also form the only return path for the main magnetic flux.

In one particular embodiment, the dewar can take the form of a group of axial spokes.

A header ring is placed at each end of the structure formed by the spokes to interconnect corresponding ends of the spokes.

This structure is then assembled into the first core in a proper manner, including proper placement to minimize heat loss.

With the arrangement described here, the demands on the refrigeration capacity of the device are reduced, since the dewar contains only superconducting windings.

Moreover, the flux loss caused by the main field flux passing through the insulating structure of the dewar bottle is significantly reduced,
The magnetic flux available for synchronous operation increases considerably.

These and other objects, features and features of the present invention will become apparent from the following description of embodiments illustrated in the accompanying drawings.

A preferred embodiment of the invention is schematically shown in FIG. 1A.

The rotating electrical machine 11 is shown in a cross-sectional view taken along a plane perpendicular to its longitudinal axis.

Although the invention is applicable to many different types of structures,
This embodiment is a cylindrical rotating electric machine.

Although the present invention is also applicable to other uses such as generators and synchronous phase advancing machines, the rotating electric machine 11 is treated here as an AC motor that performs synchronous operation and asynchronous operation.

The armature or stator 13 is made of a ferromagnetic material such as iron and is generally in the form of a cylindrical ring.

A number of slots 15 are formed in the inner circumference of the annular stator 13 and stator windings 17 are placed within these slots 15.

Inside and concentrically with the stator 13 is a generally cylindrical ring of ferromagnetic material, which forms a first core 19.

The first iron core 19 is spaced apart from the stator 13 and has a gap 2 therebetween.
1 is formed.

A conductor 23 or 25 (FIGS. 1A and 1B) is disposed within the first core 19 around its outer periphery.

These electrical conductors form the induction motor windings used during asynchronous operation during starting of the rotating electrical machine.

Two different types of conductors 23.25. The two embodiments used are illustrated.

The conductor 23 is a bar of the squirrel cage rotor winding;
5 is a bar placed in the slot 27 of the wound rotor structure.

The advantage of the squirrel cage winding is its low cost, while the advantage of the wound rotor structure is that it can be used as an auxiliary field winding in case the superconducting magnetic field is lost.

The particular type of induction winding utilized will depend on the given conditions.

A large number of dewar bottles 29 are arranged approximately in the middle of the first iron core 19 in the radial direction.

The dewar bottle 29 has an outer wall 31, an inner wall 33, and a radiation shield 35.

A vacuum is maintained between outer wall 31 and inner wall 33 to provide a thermal barrier, while radiation shield 35 helps insulate within dewar 29 from ambient temperature conditions.

The interior of the dewar bottle 29 is of course insulated from the first iron core 19.

Superconducting windings 37 (in this embodiment, a pair of superconducting windings 37 are disposed within each dewar) are located inside the dewar 29.

The superconducting winding 37 is any suitable winding having this property,
It can be of either single-strand or multi-strand type, with either continuous windings or separated segments.

Any suitable superconducting material can be used, such as niobium-titanium.

A superconducting winding is wound around a plurality of first portions 39 of ferromagnetic material.

The first portion 39 is a magnetic pole, to which the superconducting winding 37 provides magnetic flux.

Although the first portion 39 is shown as an integral part of the first core 19, it can of course also be a separately mounted portion of ferromagnetic material.

The second portion 41 of the ferromagnetic material is connected to a pair of adjacent magnetic poles, i.e., the first
Portions 39 are connected to provide a first magnetic flux path between the poles.

The second portion 41 is located between the superconducting winding 3T and the induction motor winding or conductor 23.25.

Although the second portion 41 is shown as an integral part of the first core 19, of course these portions may be connected to the superconducting windings 37 and the inductive windings 23, provided they form a flux path between the magnetic poles.
It can be made separate from both of 25.

This first magnetic flux path serves as a shunt for the relatively low frequency alternating magnetic fields that occur during asynchronous operation.

In this way, alternating magnetic fields are prevented from penetrating into the superconducting winding 31 and causing undesirable losses within it.

In addition to power loss, these alternating magnetic fields cause "quenching"
In other words, the superconducting effect may be lost.

A second magnetic flux path between a pair of adjacent magnetic poles or first portions 39 is formed by a third portion 43, 45° 47 of ferromagnetic material.

The third portion or segments 43, 45 are the first iron core 19
are integral parts of the magnetic poles, and extend from adjacent magnetic poles toward each other.

The inner ends of segments 1-43, 45 are spaced apart from each other with a gap 49 formed therebetween.

Air gap 49 forms a non-magnetically polarized area within the second magnetic flux path provided by segments 43,45.

The portion 47 extends between a pair of adjacent magnetic poles and is connected to the stator 1.
3 and the first iron core 19 in the form of a generally cylindrical annular body.

This annular body forms a second core 51 of ferromagnetic material.

The portion 47 of the second core 51 is spaced apart from the first portion 39 or pole and segment 43.45, forming an air gap 53 therebetween.

Air gap 53 forms a non-ferromagnetic zone within the second magnetic flux path that includes portion 47 .

Portion 47 is necessarily a ferromagnetic material, in this case the second
The magnetic flux path of is limited to the path through segments 43, 45 and air gap 49.

It is also possible to place the dewar bottle 29 on the innermost circumference of the first core 19 and omit the segments 43,45, in which case the second flux path includes only the portion 47 and the air gap 53.

The second iron core 51 is fixed to each other so as to rotate together with the first iron core 19.

Any suitable means for fixedly connecting the first core 19 and the second core 51 may be used, such as a spider of non-ferromagnetic material or a device such as a suitable end connection piece.

Of course, these iron cores can also be formed integrally with internal connections located outside the magnetically functional parts of the rotating electrical machine so as not to form leakage flux paths.

Power is extracted from the rotating electrical machine by shaft 55.

The shaft 55 is fixedly connected to the first core 19 and the second core 51 by a suitable device and is connected to a suitable bearing (not shown).
It is mounted in an outer box (not shown) by

When the rotating electric machine 11 is operated as an AC motor, a suitable AC current is applied to the stator winding 17 during the starting period.

The magnetic flux created by the stator windings is transferred to the induction motor conductor 2
3 or 25 to generate starting torque.

The alternating magnetic flux produced by the stator windings, especially the relatively low frequency flux produced until the rotor reaches synchronous speed,
The shunt provided by the second portion 41 prevents it from penetrating into the superconducting windings.

Almost all of the magnetic flux present during asynchronous operation is confined within this path, since the alternating magnetic flux due to the air gap 49. This is because it does not pass through the main magnetic flux path.

During steady state or synchronous operation, a superconducting winding is used so that the second portion 41 of ferromagnetic material is saturated by a strong magnetic flux.

The magnetic field produced by the superconducting windings is very strong, so the second
Until portion 41 reaches saturation, the flux shunted through second portion 41 will only be about 20 times the generated magnetic flux.

Approximately 80% of the magnetic flux generated is in the segment 43°4
5 and a second magnetic flux path through section 41 .

In this way, the magnetic flux passing within this second or main flux path can be used during synchronous operation.

The arrangement described above results in an electric motor that generates relatively large asynchronous torques for starting and yet retains most of the strong magnetic field produced by the superconducting windings for synchronous operation.

Also with this configuration, the dewar is needed only to maintain the superconducting windings at a very low temperature, with all other components operating at ambient temperature.

This, of course, reduces the required refrigeration capacity and increases the overall efficiency of the rotating electrical machine.

Moreover, by removing the dewar wall structure from the passage serving for synchronous operation of the rotating electrical machine, the amount of magnetic flux available for synchronous operation is significantly increased.

The efficiency of the rotating electrical machine will further increase.

FIG. 2 illustrates the shape of the dewar bottle 29.

In this embodiment, the dewar 29 includes a plurality of axial spokes 57 and a header ring 59 .located at each end of the axial spokes and connected to the end of each spoke.
61.

The superconducting windings 37 are located within the vessel and are provided with suitable connections for introducing cryogenic fluid into the vessel with minimal heat loss.

A suitable mounting arrangement can be provided to mount the dewar bottle 29 onto the iron core 19 with minimal heat leakage.

[Brief explanation of drawings]

FIG. 1A is a schematic cross-sectional view of one embodiment of the rotating electric machine of the present invention taken along a direction perpendicular to its longitudinal axis, and FIG.
FIG. 2 is a partial cross-sectional view showing the embodiment of FIG.
FIG. 2 is a partially cutaway perspective view of the insulating device used in the rotating electric machine shown in FIG. B; 11... Rotating electric machine, 13... Armature,
15...Slot, 17...Stator winding, 19...First iron core, 21...Gap, 23.25... Conductor, 27...Slot, 29...--Dewar bottle, 31...
・Outer wall, 33...Inner wall, 35...
Radiation shield, 3T...Superconducting winding, 39...
...First part (magnetic pole), 41... Second part, 43,45.47... Third part (43,45
...segment, 47 ... part), 4
9...Gap, 51...Second iron core, 53
...Gap, 55...Axis, 57...
・Axial spokes, 59°61...Header ring.

Claims (1)

[Claims] 1. A stator having a stator winding and a circular hole, and a stator rotatably provided concentrically within the circular hole of the stator, spaced apart from the stator with a gap in between. a substantially hollow cylindrical ferromagnetic core having a plurality of first ferromagnetic cores extending substantially radially;
a plurality of second portions extending circumferentially so as to be magnetically coupled to adjacent outer ends of the first portion to form an outer periphery of the core; an iron core that extends in the circumferential direction so as to be combined to form the inner periphery of the iron core, and has a third portion having a gap between the ends thereof in the circumferential direction; and a superconducting winding wound on the first portion. - an insulating device that surrounds the superconducting winding and insulates it from the core and the surrounding environment, and is provided in the second portion of the core at a portion close to the gap between the stator and the stator winding. A rotating electrical machine that includes a conductor that constitutes a short-circuit winding for generating a corresponding starting torque.