JPS5895803A - Superconductive electromagnet device - Google Patents

Abstract

PURPOSE:To protect a superconductive coil without affecting adversely a quench detecting system and a power source controlling system, by providing a series circuit consisting of a capacitor and a switch ON-controlled in the emission of energy between the two ends of a protective resistor, and thereby absorbing rapidly a surge voltage to be generated by the inductance of the protective resistor. CONSTITUTION:A series circuit consisting of a switch 11 and a capacitor 12 is connected between the two ends of a protective resistor 5, while the switch 11 and a switch 6 are controlled by a control device 13 in the following way. When a quench detection signal p is given, for instance, the control device 13 controls the switch 11 to be ON, while controlling the switch 6 to be OFF in a slight lag behind the time point whereat the switch 11 is turned ON. A surge voltage to be generated is absorbed beforehand in the capacitor 12 by the inductance of the protective resistor 5, and thus a superconductive coil 3 can be protected.

Description

[Detailed description of the invention] Technical field of invention The present invention relates to a superconducting electromagnet device.

Technical Background of the Invention In recent years, superconducting electromagnet devices have been used in not only stationary equipment but also rotating equipment. As is well known, a superconducting TFA stone device consists of a low-temperature container whose interior is kept at an extremely low temperature,
It mainly consists of a superconducting coil housed in this low-temperature container and a power supply device that excites this superconducting coil.

In addition to the above-mentioned elements, a device capable of switching to the persistent current mode is provided with a persistent current switch located inside the low temperature container and selectively short-circuiting both shoulders of the superconducting coil.

By the way, in such a superconducting electromagnet device, for example, when the superconducting coil transitions to a normal conduction state (quench), in order to prevent the superconducting coil from burning out, etc. It is necessary to quickly release the energy by some means to reduce the current to zero. As described above, as a means for releasing energy stored in a superconducting coil in a so-called emergency, a means for releasing energy through a protective resistor is normally adopted. In other words, in all cases of supercurrent electromagnet system #t, which constantly supplies current to the superconducting coil from an external power supply, as shown in Fig. 1, the output trend of the IT power supply and the inside of the cryogenic vessel 2 are A protective resistor 5 is connected between the leads @ 4 m and 4 b that connect the superconducting coil 3 housed in the superconducting coil 3, and when the superconducting coil 3 quenches, the lead wire
By turning off the switch 6 inserted in the middle of the superconducting coil 1, the energy that has been stored in the superconducting coil 3 is released through the protective resistor 5, and most of the energy is consumed outside the cryogenic container 2. ing. Note that even if a persistent current switch is provided between both ends of the superconducting coil 3 in the low-temperature vessel 2, a protective resistor is connected at the position shown in FIG.

Problems with the Background Art If the protective resistor 5 is connected as described above, the energy stored in the superconducting coil 3 can be transferred to the cryogenic vessel 2 in an emergency.
It can be quickly consumed outside. but,
In number 4 shown in Fig. There were problems such as destruction. That is, the superconducting coil 3 is now connected via the switch 6 as shown in FIG.
When the vL current Io is flowing, if the switch 6 is turned off at time t1, the current flows to the superconducting coil 3! fiI flows in a closed circuit from the superconducting coil 3 to the protective resistor 5 to the superconducting coil 3, attenuates over time, and finally becomes zero. On the other hand, when the switch 6 is turned off at time t1, a voltage vL is generated across the superconducting coil 3 at this time.

If the resistance value of the protective resistor 5 is R, this voltage vL is
, , = the value of IoR. However, in reality, as shown in FIG. 2(b), the above-mentioned vL
A voltage that is a superposition of Vc length and voltage V8 is generated. For the surge voltage ■8, let the inductance value of the protective resistor 5 be L,
Sui forces Chiro to turn off. The switch 6 acts like a thyristor, and as a result, an abnormally high voltage is generated across the superconducting coil 3.

Therefore, in order to solve this problem, it is possible to use a protective resistor with a sufficiently small inductance value, but as a practical matter, it is extremely difficult to manufacture a resistor with a sufficiently small inductance value.

OBJECTS OF THE INVENTION The present invention has been made in view of the above circumstances, and has the following feature: When the energy of the superconducting coil is released, the surge voltage that is about to be generated can be quickly absorbed by the inductance of the protective resistor. Another object of the present invention is to provide a superconducting electromagnet device that can maintain a superconducting coil without adversely affecting a quench detection system or a power supply control system.

Summary of the Invention The superconducting electromagnet device according to the present invention is characterized in that a series circuit including a capacitor and a switch that is turned on when energy is released is provided between both ends of a protective resistor.

Effects of the Invention Since the series circuit consisting of the above-mentioned elements is provided between both ends of the protective resistor, that is, in parallel with the protective resistor, when the energy of the superconducting coil is released, even if an abnormal voltage is generated due to the inductance of the protective resistor, it will not occur. This is absorbed by the capacitor, and no voltage higher than the above-mentioned vL is generated across the superconducting coil. therefore,
Sui on the power supply side! Even if a thyristor with a short interruption time is used as a bridge, it is possible to prevent the occurrence of dielectric breakdown of the interlayer insulation material of the superconducting coil due to abnormal voltage. Further, since there is no problem even if some inductance is present as the protective resistor, an inexpensive resistor can be used as the protective resistor.

In addition, since the capacitor is normally separated by a switch or a switch, for example, even in the case of a method that detects damage during excitation and demagnetization of a superconducting coil from changes in both temperature voltages of the superconducting coil. There is no risk that the presence of the capacitor will adversely affect quench detection, and similarly, there is no risk that the capacitor will have an effect on power supply control.

Embodiment of the Invention FIG. 3 is a circuit diagram of a superconducting electromagnet device according to an embodiment of the present invention, and the same parts as in FIG. 1 are designated by the same reference numerals. Therefore, the explanation of the overlapping parts will be omitted.

In this embodiment, a series circuit consisting of a switch 11 and a capacitor 12 is connected between both ends of the protective resistor 5, and the switch 11 and the switch 12 are connected to a control device 13.
It is controlled as follows. That is, the control device 1
3 controls the switch 11 to turn on when the quench detection signal p is applied, for example, and also controls the above-mentioned switch.

The switch σ is turned off with a slight delay from the time when the switch 11 is turned on.

Therefore, with the above configuration, when quenching occurs, the switch 6 is turned off, the switch 11 is turned on, and the capacitor 12 is connected to the protective resistor 50 yen! Since the circuit is connected to the capacitor 12, even if a surge voltage is generated due to the inductance of the protective resistor 5, this surge voltage will be
In the end, the voltage across the superconducting coil 30 is the same as the current value at which the coil 30 turns off. The resistance value R of the protection resistor 5 will not exceed the value determined by the resistance value R of the protection resistor 5 and the resistance value R of the protection resistor 5. Therefore, the superconducting coil S can be protected. Further, since the switch 11 is always off, the quench detection system and the power supply control system are not affected by the presence of the capacitor 12, and the nine effects described above can be obtained.

It goes without saying that a semiconductor switching element such as a thyristor can be used as the switch 6.11. Also,
Of course, it can also be applied to those equipped with a permanent '4-flow switch.

[Brief explanation of drawings]

Figure #11 is a circuit diagram of a conventional superconducting electromagnet device, the second
Figures (a) and (b) are diagrams for explaining problems with the device, and FIG. 3 is a circuit diagram of a superconducting TA15 device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Power supply device, 3... Superconducting coil, 5... Protective resistor, 6.11... Switch, 12... Capacitor. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (2)

[Claims] (1) Connecting a protective resistor between both ends of a superconducting coil that constitutes an electromagnet, and releasing energy -kf stored in the superconducting coil through the protective resistor when the superconducting coil is abnormal. Therefore, the above energy is (′f
The superconducting electromagnet device is characterized in that a series circuit of a capacitor and a switch that is turned on when the energy is released is provided between one shoulder of the protective resistor. Electromagnetic device. (2) The superconducting electromagnet device according to claim 1, wherein the switch is a semiconductor switching element.