JPS5952809A - Protection device of magnet coil - Google Patents

Abstract

PURPOSE:To discharge an accumulated energy in a short time and reduce the size of an equipment by a method wherein a resistor to which a switch is connected in parallel is connected to the exciting input end of a magnet coil and a contol circuit which outputs a command for regnerative driving of an exciting source and a command for opening the switch given above. CONSTITUTION:A superconducting coil 1, an exciting source 2 and a protecting resistor 4 are connected in series and a switch 3 is connected to the protecting resistor 4 so as to short circuit it. A quench detecting signal given by a quench detecter 5 is put into a control circuit 6 which is so composed that it outputs a command for regenerative driving to the exciting source 2 and at the same time a command for opening to the switch 3 in accordance with the input quench detecting signal. When quench occurs in the superconducting magnet 1, the exciting source 2 is driven in regenerative manner and at the same time the switch is opened and an accumulated energy is consumed by the protecting resistor 4 and fed back to the AC source and discharged quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection device for medically protecting an electromagnetic coil by quickly discharging accumulated energy when excitation is stopped, and particularly relates to a protection device for medically protecting an electromagnetic coil.
The present invention relates to something suitable for protecting a turtle conductor coil from damage caused by quenching.

Generally, when de-energizing an energized electromagnetic coil, there are cases where it is required to quickly release the electromagnetic energy and mechanical energy stored in the electromagnetic coil.

For example, in a superconducting coil, when a quench occurs and expands, the entire superconducting coil undergoes a phase transition to a conductive state, which causes a rapid increase in the heat generated in the coil.
There is a risk that the superconducting coil may be thermally damaged. Therefore, when a quench or the like occurs and fC occurs, the electromagnetic energy stored in the superconducting coil must be released as quickly as possible to protect the coil.

As a method of discharging the electromagnetic energy received by the electromagnetic coil, there are two methods: regenerating the excitation power source of the electromagnetic coil to regenerate the accumulated energy as electric power, and using a protective resistor to dissipate the accumulated energy. There are ways to do this.

However, since the resistance of the superconducting coil is almost zero, the output voltage of the excitation power supply is generally low voltage.
It belongs to Inuzin style. Therefore, in the case of using the regenerative operation method, the regenerative voltage must be limited to a low level according to the output voltage, so there is a drawback that the time for releasing the stored energy becomes relatively long.

On the other hand, the method using the protective resistor described above has the circuit configuration shown in FIG.
The superconducting coil 1 is connected to a J-magnetic power source 2 via a switch 3, and a holding resistor 4 is connected in parallel to the superconducting coil 1. Further, the superconducting coil 1 is provided with a quench detector 5. With this configuration, when the occurrence of quench is detected and the switch 3 is opened, the energy stored in the superconducting coil 1 is passed through the protective resistor 4 and is consumed.

Now, in the one shown in FIG. 1, the self-inductance of the superconducting coil 1 is expressed as L1, the resistance value of the protective resistor 4 is expressed as 几1,
When the initial value of the current bif flowing through the superconducting coil 1 when the switch 3 is opened is set to 1°, the discharge current flowing through the circuit of the protective resistor 4 is calculated as shown in the following equation (1). I can do a lot of things. , Incidentally, ε in formula (1) is the base of the natural logarithm, and t is time.

-One.

I-■. SL...(1) As is clear from equation (1), the emission current I is rapidly attenuated over time, but the attenuation is time-dependent, and it is difficult to rapidly release the stored energy. This is achieved by making , as large as possible.

However, since the value of it must be determined so that the back electromotive force I.IL generated by I is under the pressure wind of the superconducting coil l, the emission time is limited. In addition, since the protective resistor 4 consumes all the stored energy of the superconducting coil, if the stored energy reaches the GJ (giga joule) class,
There is a drawback that the peripheral equipment f (for t+lJ, cooling equipment, etc.) of the protection resistor and the maintenance resistor becomes an extremely large device with a thickness of 8i.

The present invention has been made in view of the above-mentioned drawbacks, and its purpose is to provide an electromagnetic coil such as a superconducting coil that can rapidly release the stored energy and that can reduce the size of the device. The aim is to provide replacement equipment for

The present invention is characterized in that a resistor connected in parallel with a switch is inserted and connected in series to the excitation input terminal of an electromagnetic coil connected to an excitation power supply capable of regenerative operation, and the By providing the control circuit 611' with a control circuit that outputs a regenerative operation command of the power source and an opening command of the switch, it is possible to rapidly release the regenerative energy and to achieve miniaturization of the device. That is.

Hereinafter, the present invention will be explained based on illustrated examples.

FIG. 2 shows a circuit diagram of an embodiment of the present invention. Components in the figure that are denoted by the same reference numerals as in FIG. 1 have the same structure.

As shown in Fig. 2, a superconducting coil 1 and an excitation power source 2
and a protection resistor 4 are connected in series, and the switch 3 is connected to short-circuit the protection resistor 4. In addition, the quench detection signal output from the quench detector 5 is input to the trace J control circuit 6, and this control circuit 6 issues a regenerative operation command to the excitation power source 2 based on the input quench detector signal. At the same time, switch 3
The circuit is configured to output an open circuit command.

With this configuration, when a quench occurs in the superconducting coil 1, the excitation power source 2 is operated regeneratively, the switch 4 is opened at the same time, and the stored 4λ energy is consumed by the protective resistor 4. At the same time, it is regenerated to the AC power source and rapidly released. 4 streams of release at this time■
The resistance value of the protective resistor 4 is R3, and the excitation power source 4 is
If the pressure (inverter voltage) is E, it can be expressed by the following equation (2).

That is, the first term on the right side of equation (2) represents current attenuation due to the protective resistor 4, and the second term represents current attenuation due to regenerative operation.

Therefore, as is clear from equation (2), the present example has the effect that the emission current C can be attenuated more rapidly than in equation (1).

Also, originally bl! According to example i, since a piece of livestock energy is regenerated, the stored energy consumed by the protective resistor is reduced, and the current decay time is short, so the protective resistor and the surrounding area of the protective resistor are This has the effect that the device can be made smaller in size. This has the effect of achieving energy savings and improving economic efficiency.

In order to more specifically explain the effects of the present invention, comparative data of experimental values is shown in Table 1.

In Table 1, VLMAX represents the maximum voltage applied to the superconducting coil 1 and corresponds to 4 voltages.

In addition, To is the time required for the emission current ■ to become zero, QR
represents the energy consumed in the mining resistor 4.

As explained above, according to the present invention, the energy stored in the electromagnetic coil can be rapidly released, the device can be made smaller and energy saving can be achieved, and the economical efficiency can be improved. , which is particularly effective in preventing damage to superconducting coils.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing an example of an electromagnetic coil protection device.
FIG. 2 is a circuit diagram of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Super 1-conductor coil, 2... Excitation power supply, 3... Switch, 4... Protection resistor, 5... Quench detector,
6...Control circuit.

Claims (1)

[Claims] 1. The excitation power source for the electromagnetic coil is formed to enable regenerative operation, and a protective resistor with a switch connected in parallel is inserted and connected in series between the excitation power source and the electromagnetic coil, and based on the given command - An electromagnetic coil protection device characterized in that the excitation power source is provided with a control circuit that outputs a regenerative operation command and a circuit opening command to the switch.