JPS5815924B2 - Superconducting coil excitation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a superconducting coil excitation device for exciting a superconducting coil.

There are two methods for exciting a superconducting coil in a cryogenic container: a method in which lead wires are led from a DC power supply to the cryogenic container and excited with a large current, and a method in which a flux pump device is used to excite the superconducting coil.

However, in the method of excitation using a DC power supply, the lead wire is guided into a cryogenic container at a temperature of 4.2° from the room temperature of approximately 300°K, so a large amount of heat enters the lead wire. Joule heat is generated, but it is proportional to the square of the current, so a considerable amount of heat will enter the cryogenic container.

Therefore, although the time to excite the superconducting coil is quick, a considerable amount of heat enters the cryogenic container, which poses a problem in terms of cooling efficiency.

The method of exciting a superconducting coil using a flux pump device requires less current to flow in from the outside than the method using a DC power supply, so the lead wires can be thinner, and there is also less heat intrusion from the outside (and less Joule heat). However, there is a disadvantage that it takes a long time to excite the superconducting coil.

An object of the present invention is to provide a superconducting coil excitation device that eliminates the above-mentioned drawbacks, excite a superconducting coil in a short time, allows fine adjustment of the excitation of the superconducting coil, and minimizes heat intrusion into the cryogenic container. It is about providing.

In the present invention, a series circuit in which a persistent current switch for a DC power source and a current reversal detection circuit are connected in series is connected in parallel to a superconducting coil of a flux pump device, and a DC power source is connected in parallel to the series circuit. It is designed to excite a coil.

Hereinafter, typical embodiments of the present invention will be described using the drawings.

As shown in FIG. 1, a superconducting coil excitation device 1 according to the present invention includes persistent current switches 4.5 and current reversal detection circuits 6 at both ends of a secondary winding 3 of a transformer 2.
．． 7 are connected in series, one end is connected to the neutral point of the secondary winding 3, the other end is connected to the superconducting coil 8, and the voltage waveform control circuit 9 is connected to the transformer 20 primary winding 10. In the type flux pump device 11, a series circuit 1 is formed by a persistent current switch 12 for DC power supply and a current reversal detection circuit 13.
4 is formed and connected in parallel to the superconducting coil 8, and a DC power source is connected in parallel to the series circuit to supply current to the superconducting coil 8.

Next, the operation will be explained.

The persistent current switch 4.5 and the persistent current switch 12 for DC power supply are turned off.

A current is passed through the superconducting coil 8 from the DC power supply 15 to perform rapid excitation.

After being excited to the permissible current, the persistent current switch 12 for the DC power source is turned on to create a persistent current between the superconducting coil 8 and the series circuit 14, and then the DC power source 15 is disconnected, and the current flows in the direction 16.

Next, the persistent current switch 4 of the rectifying flux pump device 11 is turned on, and the persistent current switch 12 for DC power supply is turned on.
A small voltage is applied to the primary side of the transformer 20 so that the current direction can cancel out the current flowing in the transformer 20.

The inductance of the secondary winding 3 of the transformer 2 is small and
Persistent current switch 4 and persistent current switch 1 for DC power supply
Since persistent current switch 2 is in the on state, persistent current switch 4 and persistent current switch 1 for DC power supply are activated even by a minute voltage of the primary winding.
2, a large current flows in direction 17.

As a result, the current flowing through the DC power persistent current switch 12 becomes zero, and when the current reversal detection circuit 13 detects this state, the DC power persistent current switch 12 is turned off, and this detection signal is sent to the voltage waveform control circuit 9. send to

By this operation, the charging current of the superconducting coil 8 supplied from the DC power supply 15 is transferred to the closed circuit on the persistent current switch 4 side.

Thereafter, the excitation of the superconducting coil 8 can be finely adjusted by operating the rectifying flux pump device 11 normally.

Similarly, the voltage waveform control circuit 9 is configured to output a programmed waveform.

In the above embodiments, the case of a rectifying type flux pump device has been described, but any type of flux pump device such as a rotating magnetic field type flux pump device may be used.

As is clear from the above explanation, if the superconducting coil excitation device according to the present invention is used, the superconducting coil can be rapidly excited using a DC power supply until a predetermined value is reached, and then the superconducting coil is excited using a flux pump device. As a result, the excitation time of the superconducting coil can be shortened, and the excitation can be finely adjusted.Furthermore, once the superconducting coil has been excited to a predetermined value, a flux pump device is used, so that the superconducting coil cannot be moved into the cryogenic container. Since the amount of heat infiltration is reduced, cooling efficiency is improved, and various other excellent effects can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a typical embodiment of a superconducting coil exciting device according to the present invention. DESCRIPTION OF SYMBOLS 1... Superconducting coil excitation device, 4.5... Persistent current switch, 6.7.13... Current reversal detection circuit, 8... Superconducting coil, 11... Rectifying Franks pump device, 12... Persistent current switch for DC power supply, 14... Series circuit, 15...DC power supply.

Claims (1)

[Claims] 1. In a device that has a flux pump device that excites a superconducting coil with an excitation circuit via a persistent current switch, a series circuit with a persistent current switch for a DC power supply and a current reversal detection circuit that controls the persistent current switch for a DC power supply. A superconducting coil excitation device, characterized in that the superconducting coil is configured such that the series circuit is connected in parallel to the superconducting coil, and a DC power source is connected in parallel to the series circuit to excite the superconducting coil.