JP2509633B2 - Solenoid type AC superconducting coil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a solenoid type AC adopted as a constituent element of an AC device such as a transformer or a generator used at a commercial frequency (50 to 60 Hz). For superconducting coils for automobiles.
More specifically, it relates to a highly practical superconducting coil in which AC loss is greatly reduced.

[Conventional technology and its problems]

With the development of ultra-thin multi-core superconducting wires, AC superconducting coils, which were conventionally limited to pulse applications of about several Hz, are now being used for commercial frequencies.

By the way, in order to use the superconducting coil with an alternating current, it is necessary to reduce the AC loss under energization and prevent the coil from generating heat.

The AC loss can be divided into the one caused by the performance of the superconducting wire and the one caused by the movement of the wire due to the electromagnetic force. Among them, the former cause has been mostly removed by the recent high performance of the superconducting wire. Therefore, in order to realize a practical AC superconducting coil, it is required to remove the remaining causes. In response to this requirement, most of the coils of this kind that have been produced so far are of a type in which an insulating superconducting wire is tightly wound or an insulating spacer is inserted between layers. And
They are cooled by maintaining contact with a refrigerant (eg liquid helium) to prevent heat generation.

However, in the coil having the above-described structure, the stationary force of the wire is determined by the winding tension at the time of winding,
Since the movement of the coil wire easily occurred due to the electromagnetic force during energization, heat generation due to the entire or local movement of the winding causes AC loss that exceeds the cooling capacity, and the coil performance does not exceed its maximum capacity. A so-called quench phenomenon that causes the entire coil to transition from the superconducting state to the normal conducting state is often observed.

On the other hand, in order to eliminate mechanical movement of the winding part, a method of impregnating the winding part with epoxy resin etc. and hardening the whole with the resin has been conventionally adopted, but this method is at most about several Hz. Can only withstand use. Because the surface of the inner layer winding is hidden by the impregnated resin, the direct cooling by the refrigerant is limited to only the surface of the winding part, and the AC loss heat generated internally by several tens Hz is sufficiently released. Can not do it. Therefore, the quench described above occurs. This kind of problem is especially serious when the coil capacity is large, and no matter how much the AC loss is reduced, thermal energy is accumulated with the lapse of time and eventually leads to quenching.

Therefore, an object of the present invention is to provide an alternating-current superconducting coil which is effective as a measure against the above problem.

[Means for solving problems]

The solenoid type AC superconducting coil of the present invention is formed by winding a superconducting wire having an ultra-fine multicore filament with a predetermined gap in the coil axial direction, and insulating spacers between the layers of the winding at a predetermined pitch in the circumferential direction. And the spacers bond the upper and lower layers to each other, and
The winding is adhered and held in a groove provided in the insulating spacer at a winding pitch, and a gap formed between windings of each layer between adjacent insulating spacers serves as a cooling channel into which a refrigerant flows. However, it has a feature.

[Action]

Since the coil wire is held in a state of being substantially embedded between the insulating spacers of the layers laminated and adhered in the coil radial direction, it has excellent stationary stability and is unlikely to cause mechanical movement.

In addition, since a predetermined distance is maintained between the coil wire rods in both the coil axial direction and the coil radial direction, the wire rods do not rub against each other even if distortion occurs due to electromagnetic force in the unsupported portions of the wire rods, and the wire is closely wound. The heat generated due to the friction of the wire material seen in the coil does not occur.

Further, the cooling channel between the insulating spacers has excellent openability to the outside, and since the wire rod directly contacts the cooling in this portion, the effect of discharging the AC loss heat is sufficiently ensured also in the inner layer winding portion. It is preferable that the width of the insulating spacer is fixed so that the wire member is firmly fixed, because the wire member that is heated by the AC loss is cooled.

〔Example〕

One embodiment of the solenoid type superconducting coil of the present invention will be described with reference to the attached drawings.

1 is a superconducting wire having an ultrafine multifilamentary filament, and 2 is a bobbin (that is, a bobbin) made of glass fiber reinforced plastic or the like in which loss due to alternating current does not occur. On the winding cylinder of the bobbin 2, first, insulating spacers having grooves 3 extending in the winding direction provided at a constant pitch in the coil axial direction are attached at a predetermined pitch in the circumferential direction. Then, the wire 1 is wound on the coil 3 at intervals in the axial direction of the coil so that the wire 1 fits in the groove 3. Further, the spacer 4 is installed again on the winding of the first layer, and thereafter, the same work as that of the first layer is repeated while turning the winding direction until the required number of additional layers is obtained, and a coil having a predetermined diameter is obtained. It's finished.

Further, during this work, the wire 1 is coated with an adhesive 5 such as an epoxy resin and adhered in the groove 3 of the spacer. The spacers 4 of the respective layers stacked in the coil radial direction are also bonded and integrated with each other via the adhesive 5, so that the wire 1 is firmly restrained in the spacer portion. The same constraint effect can be obtained even if the groove 3 is provided in the joint interface portion of the spacer 4 in half. Reference numeral 6 denotes a cooling channel directly communicating with the outside, through which the refrigerant flows.

In addition, the superconducting wire 1 used is an ultrafine multifilamentary filament made of an alloy of Nb and Ti, or a material in which a third element is added to the alloy, Nb ₃ Sn, V ₃ Ga, Nb ₃ Si, V Practical wire rods made of compound materials such as ₂ Hf and Nb ₃ Al are preferable. This is because these wires have a small capacity and can flow a large current.

Further, the multifilamentary filament preferably has a diameter of 1 μm or less. This is because the magnetization loss due to the thickness of the filament (this is the main factor of AC loss) is extremely small.
If the filament diameter is 1 μm or more, it is difficult to make an AC coil.

In addition, when the spacer 4 is provided with radial grooves facing the inner surface of the bobbin collar and both ends are inserted into the grooves for positioning, the workability during winding is excellent. However, the coil of the present invention may be used by forming it on the winding core, removing the winding core, and then fixing the coil on the core instead of the winding core. , The bobbin itself is not mandatory.

Hereinafter, more detailed examples of the present invention will be described together with comparative examples.

Using a superconducting wire 1 having a wire diameter of 0.36 mφ, an insulating spacer 4 having a width W = 2 mm and a groove pitch P = 1 mm shown in FIG. 1 is provided with a gap S = 2 mm (this is the distance between the innermost layers and the outer layer). Is the inner diameter arranged with the value of S increasing slightly due to the difference in circumference.
A coil A of the present invention having a diameter of 50 mm, an outer diameter of 110 mm and a height of 100 mm was produced. Also, the same wire is tightly wound and has an inner diameter of 50 mm and an outer diameter of 90 m.
A resin-impregnated comparison coil B having a height of 50 mm and a height of 50 mm was also prepared.

 The capacities of these coils are shown in comparison with the table below.

The target value achievement rate of coil A for voltage and current is 100%
However, the coil B is far away from the target value.

 In addition, there is a 30 times difference in AC loss.

As described above, even if the inductance is the same, the coil of the present invention has a tendency to have a slightly larger size, but the performance is significantly improved as compared with the conventional coil.

〔effect〕

The coil of the present invention constituted as described above is particularly effective in the fields of AC transformers and generators used at commercial frequencies.

That is, in the AC transformer configured by combining a plurality of coils, a complicated electromagnetic force acts on the coil winding portion due to the interaction of the coils, and thus a delicate mechanical movement is likely to occur.
However, according to the present invention, the insulating spacer surely prevents the movement, and since the wire itself is so-called loosely wound, mutual friction does not occur, and therefore, the local movement due to the subtle movement of the winding portion is caused. Fever hardly occurs, and quenching due to this is effectively prevented.

In addition, when a current of 50 to 60 Hz is applied, AC loss is constantly generated inside the coil, but the heat is absorbed quickly because the wire rod directly touches the refrigerant flowing into the cooling channel between the layers. Also, quenching due to poor cooling efficiency is prevented.

Further, particularly when the coil is used for a generator as a winding of an armature, the size of the coil is increased, so that the requirements for stationary stabilization of the winding and efficient cooling are further increased. According to this invention,
By sufficiently meeting the demand, it is possible to make a great contribution to making the generator completely superconducting.

[Brief description of drawings]

FIG. 1 is a perspective view showing a part of an example of a superconducting coil according to the present invention, and FIG. 2 is a view showing a part of a radial cross section thereof,
FIG. 3 is a view showing a part of the cross section along the coil axis, and FIG. 4 is an enlarged view of a part of FIG. 1 ... Superconducting wire, 2 ... Bobbin, 3 ... Spacer groove, 4 ... Insulating spacer, 5 ... Adhesive, 6 ... Cooling channel.

Claims (1)

(57) [Claims] 1. An insulating spacer having grooves formed at the same pitch as the winding pitch on a winding frame is arranged in a vertically extending state at a predetermined pitch with a gap in the circumferential direction of the coil, and has an ultrafine multicore filament. The superconducting wire is wound at a predetermined interval in the coil axial direction while adhering to the inside of the insulating spacer and turning in the winding direction at both ends of the coil, and the insulating spacer placed between the layers of the winding is Solenoid type AC superconducting coil in which coils are laminated in the radial direction of the coil and adhered to the upper and lower spacers, respectively, and the gaps formed between the windings of the adjacent insulating spacers form cooling channels into which the refrigerant flows. .