JP2001339879A - Superconducting coil system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a superconducting coil system capable of improving the reliability thereof and attaining footprint and economical advantages. SOLUTION: This superconducting coil system consists of a superconducting coil 1, a DC power source 4 magnetizing/demagnetizing the superconducting coil 1, a bus bar 8 connecting the superconducting coil 1 and a current lead 3, and a cable 9 connecting the current lead 3 and the DC power source 4. At least one of the bus bar 8, the current lead 3, or the cable 9 is formed out of a superconductor. The superconducting coil system is provided with a feed line 10 for supplying current from the DC power source 4 to the superconducting coil 1, and a means for shifting part or the whole of the feed line 10 to a normal conducting state forcibly, and part or the whole of the feed line 10 is normal conducted by the means for shifting to normal conduction under abnormal conditions of the system to absorb energy accumulated in the superconducting coil 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting coil system using a superconducting coil.

[0002]

2. Description of the Related Art With the development of superconducting technology, the capacity of superconducting coils has been increasing in recent years. Systems using superconducting coils include fusion, SMES, accelerators, M
RI and the like. What is important in practical use of these systems is protection of the entire system including the superconducting coil.

FIG. 3 shows an example of a main circuit configuration of a conventional superconducting coil system.

In FIG. 3, reference numeral 1 denotes a superconducting coil accommodated in a cryostat 2 together with a cooling medium such as liquid helium. The superconducting coil 1 is supplied with a direct current through a current lead 3 penetrating the inner and outer walls of the cryostat 2 in a liquid-tight manner. Power supply 4
It is connected to the. A DC cutoff switch 5 is provided in the output circuit of the DC power supply 4, and a protection resistor input switch 6 and a protection resistor 7 are connected in series with the superconducting coil 1.

In the superconducting coil system having such a configuration, the superconducting coil is usually excited by the DC power supply 4 after the DC cutoff switch 5 is turned on, and demagnetized by opening. When an abnormality occurs in the system, the protection resistor input switch 6 is turned on, and the protection resistor 7 is inserted in parallel with the superconducting coil 1, so that the energy stored in the superconducting coil is absorbed by the protection resistor 7.

[0006]

As described above, in the conventional superconducting coil system, when the superconducting coil 1 is protected, a switch 6 for turning on a protection resistor is required. The equipment becomes larger. This is undesirable from the standpoint of system reliability, installation space and economy.

[0007] In addition, there is an idea of enthalpy protection in which the normal conduction region is quickly propagated to the entire coil during protection, and energy is consumed by electric resistance in the coil. However, since the coil itself is complicated, reliability is reduced. There is a problem that it decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has been made to improve the reliability of a system and
It is an object of the present invention to provide a superconducting coil system that is economically advantageous in installation space and economical.

[0009]

According to the present invention, a superconducting coil system is constituted by the following means to achieve the above object.

The invention corresponding to claim 1 comprises a superconducting coil, a DC power supply for exciting or demagnetizing the superconducting coil,
A busbar connecting the superconducting coil and the current lead, a cable connecting the current lead and the DC power supply,
And at least a portion of the bus bar or the current lead or the cable is made of superconducting power, and a power supply line for supplying current from the DC power supply to the superconducting coil; Means for shifting to an activated state, and when the system is abnormal, the normal-conducting transition means causes part or all of the power supply line to be in normal conduction to absorb energy stored in the superconducting coil.

According to a second aspect of the present invention, in the superconducting coil system according to the first aspect of the present invention, the normal-conducting transition means is a heating means using a heater for heating a part or all of the power supply line.

According to a third aspect of the present invention, in the superconducting coil system according to the first aspect of the present invention, the normal-conducting transition means applies a critical field or more to a part or all of the power supply line. Field generating means.

According to a fourth aspect of the present invention, in the superconducting coil system according to the first aspect of the present invention, the normalization transition means applies a high frequency generated from an induction coil to a part or all of the power supply line. Means of generation.

According to a fifth aspect of the present invention, in the superconducting coil system according to the first aspect of the present invention, the normal-conducting transition means generates a vibration by mechanically hitting or vibrating a part or all of the power supply line. Means.

According to a sixth aspect of the present invention, in the superconducting coil system according to any one of the first to fifth aspects of the present invention, there is provided a switching device for short-circuiting between power supply lines on the power supply side when the DC power supply is abnormal. Provide a switch.

According to a seventh aspect of the present invention, in the superconducting coil system according to any one of the first to fifth aspects, the DC power supply is a bridge connection of a semiconductor element for converting AC to DC. It is composed.

According to an eighth aspect of the present invention, in the superconducting coil system according to the seventh aspect of the present invention, a bypass pair circuit for short-circuiting a conversion circuit by the semiconductor element when the DC power supply is abnormal is formed.

According to the superconducting coil system according to the first to eighth aspects of the present invention, at the time of protection, part or all of the superconducting power supply line is forcibly converted to normal conduction by the heat of the heater and the like, and the electric power is supplied. Since the energy stored in the coil is absorbed by the resistor, there is no need for an open element provided in the electric circuit connecting the DC power supply and the superconducting coil as in the past, and the coil can be complicated as in enthalpy protection. Therefore, a highly reliable protection circuit can be constructed.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of a superconducting coil system according to the present invention. The same parts as those in FIG.

In FIG. 1, reference numeral 1 denotes a superconducting coil accommodated in a cryostat 2 together with a cooling medium such as liquid helium, and the superconducting coil 1 penetrates at least partially through the inner and outer walls of the cryostat 2 in a liquid-tight manner. It is connected to a DC power supply 4 via a lead 3.

That is, at least a part of the superconducting coil 1 in the cryostat 2 and the superconducting current lead 3 are connected by a superconducting bus bar 8, and between the superconducting current lead 3 and the DC power supply 4 is a superconducting cable 9. Connected.

The DC power supply 4 is an AC / DC converter constructed by connecting a semiconductor element for converting AC to DC in a bridge.

In the superconducting coil system having such a configuration, the heater 11 is wound around a part of the power supply line 10 of the superconducting bus bar 8, the superconducting current lead 3 and the superconducting cable 9, here a part of the superconducting cable 9, and 11 is connected to a heating power supply 12.

Although not shown, the superconducting cable 9 is covered with a heat insulating material and is cooled in a superconducting state by a cooling medium flowing in the pipe. Also, the heater 11
When the system is protected, the superconducting cable 9 is heated by a protection signal from a control device (not shown) to forcibly switch to normal conduction, so that the heat capacity enough to absorb the energy existing in the superconducting coil 1 is obtained.

In the superconducting coil system having such a configuration, at the time of normal operation, at least a part of the power supply line 10 including the superconducting cable 9, the superconducting current lead 3, the superconducting bus bar 8, and the like is in a superconducting state. A current flows through the power supply line 10 to the superconducting coil 1. In such a state, when an abnormality occurs in the system and a protection signal is input to the heating power supply 12 from a control device (not shown), the heater 11 is energized by the heating power supply 12, and the heat at that time causes the power supply line 10 to be heated. Is forcibly changed to normal conduction, and the energy stored in superconducting coil 1 is consumed by its electric resistance.

Therefore, the stored energy of the superconducting coil 1 can be consumed without using an open element in the circuit connecting the DC power supply 4 and the superconducting coil 1, and even if the stored energy of the superconducting coil 1 becomes large. Unlike the case where the protection device can be downsized and energy is consumed by propagating the normal conducting region for the superconducting coil 1 to the entire coil at the time of protection and energy is consumed, a highly reliable protection circuit is constructed without complicating the coil. be able to.

FIG. 2 is a circuit diagram showing a second embodiment of a superconducting coil system according to the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. State.

In the second embodiment, as shown in FIG. 2, a short circuit is formed on the DC power supply 4 side, and when an abnormality occurs in the short circuit, the switch is closed by a protection signal from a control device (not shown). 13 is provided.

In the superconducting coil system having such a configuration, the switch 13 is open during normal operation.
The power supply line 10 including the superconducting cable 9, the current lead 3, the bus bar 8 and the like is in a superconducting state, and the current flows from the DC power supply 4 to the superconducting coil 1 through the power supply line 10.

In such a state, an abnormality occurs in the system, the switch 13 is closed by a protection signal from a control device (not shown), and at the same time, the heater 11 is energized by the heating power supply 12 and the superconductivity is generated by the heat at that time. A part of the cable 9 is forcibly made normal. As a result, the current flows through the power supply line 10 in which a part of the superconducting cable 9 is forcibly changed to the normal conduction and the short circuit formed by the closed circuit of the switch 13.

Therefore, since the energy stored in the superconducting coil 1 is consumed by the power supply line 10 which is made into a normal conduction, the protection of the whole system can be constructed as in the first embodiment. Also, since only short-circuit elements are used,
Even if the DC power supply 4 has an abnormality, a highly reliable protection system can be realized.

In the above embodiment, a bypass pair (BPP) circuit is formed on the bridge circuit side of the semiconductor element constituting the DC power supply 4 instead of the short-circuit switch, and the stored energy of the superconducting coil 1 is passed through this BPP circuit when the system is abnormal. The same effect as described above can be obtained even if the flow is performed.

In the above embodiment, the power supply line 1
Although the normal electric conduction is forcibly applied by applying the heat of the heater 11 to a part of the power supply line 0, a method of realizing the normal electric conduction is to provide a magnetic field generator near the power supply line 10 and to supply the electric power from the magnetic field generator to the power supply line. It is also possible to apply a magnetic field equal to or more than the critical magnetic field to a part of 10 to make it normal conducting.

Further, a high frequency generator composed of an induction coil is provided in the power supply line 10 so that a high frequency generated by the high frequency generator is supplied to the power supply line 10 in the event of a system abnormality so that the power supply line 10 is made to be in normal conduction. The power supply line 10 may be mechanically vibrated to provide normal conduction when a system abnormality occurs by providing a device.

Further, a current higher than the critical current may be supplied to the power supply line 10 in the event of a system abnormality so that normal conduction is achieved.

On the other hand, in the above embodiment, the power supply line 10
Although the superconducting cable 9 has been described as an example of a part of the superconducting cable 9 as a part for making the part normal conducting, the current lead 3 or the superconducting busbar 8 may be used. It may be a conductive part or a power supply line 1 including these parts.
All of the zeros may be made to be in normal conduction.

In the above embodiment, the superconducting coil 1
Has been described in the cryostat 2 together with the cooling medium. However, in the case of using a tubular superconducting coil and flowing the cooling medium through the coil for cooling, the cooling medium contained in the cryostat 2 is Not required.

[0039]

As described above, according to the present invention, since a circuit connecting a DC power supply and a superconducting coil is not provided with an open element, it is possible to reliably protect a current route, and not to use a coil. Since some or all of the power supply lines have an energy absorption function,
A highly reliable superconducting coil system can be provided without complicating the coil.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of a superconducting coil system according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the superconducting coil system according to the present invention.

FIG. 3 is a circuit diagram showing a conventional superconducting coil system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Superconducting coil 2 ... Cryostat 3 ... Current lead 4 ... DC power supply 8 ... Superconducting busbar 9 ... Superconducting cable 10 ... Supply line 11 ... Heater 12 ... Heating power supply 13 ... Short circuit switch

Claims (8)

[Claims] 1. A superconducting coil, a DC power supply for exciting or demagnetizing the superconducting coil, a busbar connecting the superconducting coil and a current lead, a cable connecting a current lead and the DC power supply, and the busbar Or at least a part of the current lead or the cable is made of superconducting, a power supply line for supplying current from the DC power supply to the superconducting coil, and a part or all of the power supply line is forcibly brought into a normal conduction state. A superconducting coil, characterized in that when the system is abnormal, the normal conduction transition unit causes part or all of the power supply line to become normal conducting and absorbs energy stored in the superconducting coil. system. 2. The superconducting coil system according to claim 1, wherein said normal-conductivity transition means is heating means using a heater for heating a part or all of said power supply line. 3. The superconducting coil system according to claim 1, wherein said normal-conducting transition means is a critical field generating means for applying a magnetic field equal to or greater than a critical field to a part or all of said power supply line. Superconducting coil system. 4. The superconducting coil system according to claim 1, wherein said normal-conducting transition means is a high-frequency generating means for applying a high frequency generated from an induction coil to a part or all of said power supply line. Coil system. 5. The superconducting coil system according to claim 1, wherein said normal-conducting transition means is vibration generating means for mechanically hitting and vibrating a part or all of said power supply line. system. 6. The superconducting coil system according to claim 1, further comprising an on / off switch for short-circuiting between power supply lines on the power supply side when the DC power supply is abnormal. Superconducting coil system. 7. The superconducting coil system according to claim 1, wherein the DC power supply is configured by bridge-connecting a semiconductor element for converting AC to DC. Superconducting coil system. 8. The superconducting coil system according to claim 7, wherein a bypass pair circuit for short-circuiting a conversion circuit formed by said semiconductor element when said DC power supply is abnormal is formed.