JPS5897806A - Superconductive magnet protection device - Google Patents

Abstract

PURPOSE:To prevent the generation of abnormal high voltage, when normal conductive transfer generates, and convert the accumulated energy into the other form of energy as rapid as possible, by using a rotary machine as the load for emitting the accumulated energy. CONSTITUTION:Since the rotary machine 7 performs the mutual conversion between electrical energy and mechanical energy and is all constituted of a rotor and a stator in the structure, the rotor has the moment of inertia in a considerable scale. This moment of inertia can store the rotational energy in the form of kinetic energy. When the voltage over the fixed level is detected in a superconductive magnet 3 by a voltage detector 6, and a switch 2 opens, electromotive force is generated in a reverse direction. But, even when this electromotive force is impressed on the rotary machine 7 via a diode 4, the rotor stands still at that point, and therefore the impedance of the rotary machine 7 is only a winding resistance resulting in the approximate short-circuit between A and B.

Description

Detailed Description of the Invention The present invention provides a superconducting magnet image I for preventing an electromagnet from being destroyed by magnetic energy released when the superconducting state of the superconducting magnet is broken for some reason.
It concerns an Il device.

In recent years, superconducting magnets have entered the practical stage in various S* industries, and are used for nuclear fusion*, MHD power generation, high-energy particle acceleration, high-density energy storage, and magnetic levitation trains.

They are used in large-scale or high-performance applications such as convergent electron lenses using electron beams, medical writing equipment, and laser power layers, and their applications are wide-ranging.

These electromagnets rarely exist as individual electromagnets, and are mostly used in systems such as power supply systems, control systems, control systems, or ergonomics systems, so they are used in superconducting systems. In order to protect the magnets, there was a risk of damage to each of these groups in the conventional high voltage protection device.

Originally, four superconducting bodies had superconducting properties, that is, normal electrical resistance or zero properties within their critical current, critical magnetic field, and critical temperature range, and because of their high current density and high magnetic field resistance, It becomes possible to store a huge amount of magnetic energy, making it possible to manufacture large-scale electromagnets.

However, superconducting magnets can essentially maintain their superconducting state mt- only within the range of the three critical conditions mentioned above, but the property of the four superconducting bodies is that they generate heat K[! Therefore, depending on the cooling and heat transfer conditions, it may not be possible to stably hold a large amount of magnetic energy even if the critical conditions mentioned above are met. A release of energy occurs in the courier. When such a situation occurs, it is necessary to quickly and effectively extract the stored magnetic energy in the form of electrical energy.

Figure 1 shows the principle of how a conventional energy S harvesting device extracts magnetic energy and protects a superconducting magnet.
Electric current is passed from superconducting magnet 3 to superconducting magnet 3, and magnetic energy is stored at the same time.

At this time, the superconducting magnet 3 is excited while being monitored by the voltage detector @ to make sure that it is being normally excited.

If a normal conduction transition or the like occurs in the superconducting magnet 8 for some reason and a voltage higher than the set level in the voltage detector 6 is detected, - if the switch 2 is controlled to open by a device not shown; At this time, the relationship between the positive pole B and the negative pole B of the superconducting magnet 3 is reversed, and the voltage becomes higher on the negative pole than the positive pole A, and the diode 4 is in the forward direction, so the electromagnetic energy stored in the superconducting magnet 3 is flows out from the protective resistor SK through the diode 4, and due to the output of the protective resistor S, [
It cost 5K to be consumed.

As a prerequisite for the operation of the conventional protection circuit as described above, the operation must be carried out before the transition to normal conductivity or abnormal voltage is sufficiently small as determined by the voltage detector 6, otherwise, the operation of The magnet 3 is susceptible to heat generation, which may lead to damage to the magnet.

Therefore, the time constant of energy harvesting is very important, and as mentioned above, this time constant is required to be small.

Now, assuming that this time constant is aimed at τ (seconds), the relationship between the maximum value of the generated voltage V, the current when the ItM device 2 is open ■ (A), and the energy E stored in the superconducting magnet 3 is as follows. Noyo K
Become.

τ=1 ・・・・・・・・・−・・・・・・(sec
)・・・・・・(2) E,=TL■,・・・・・・・・・−・・・・・・[jo
u1c]...(3) (L is superconducting magnet 3
(B is the inductance, and B is the S resistance value.) As is clear from equation (1), if the time constant τ is made small in order to quickly release the stored magnetic energy, the maximum value vm of the generated voltage becomes very large. However, if we take the example of superconducting 11:fllK, which is currently relatively large, as J66, l, = 60MJ, I@-JOOOOm, the maximum value of the generated voltage is as follows. The following equation becomes 5.

v, = 2Xlo, x7 = 6 x 104/τ(v)・song・(
1) The maximum value of the generated voltage VaK is limited due to the structure of the superconducting magnet 3, and even if it is for the purpose of maintaining the electromagnet,
The time constant τ cannot be made arbitrarily small.If T is made small in order to speed up the energy recovery, the holding S resistance R (Ω) has to be made large, and as a result, a very large voltage is generated when the switch 2 is opened. do. This generated voltage causes the superconducting magnet 3 to
There was no end to accidents in which the interior, power supply, and control systems were destroyed.

Keimei's research was made to solve these problems, and uses the Li transmission as an active element to replace the I resistance, and provides a highly safe superconducting magnet image system. It is.

As mentioned above, superconducting magnets are protected by K.

If the protection 1111 attempts to recover energy in a short period of time, a high voltage will be generated. Therefore, the resistance value of the protective resistor must be relatively large.

The second m is a graph showing the relationship between the generated voltage and the time constant, and the broken line τ1. τ1. As shown in 5, 60M with a time constant of 1 second
To recover the stored energy of J, a voltage of 60 KV is generated, and even with a time constant of 10 seconds, a voltage of 6 KV is generated.

Assuming that the resistance value of the protective resistor at the time of 1 second coverage is L = 30H,
8=309 is required, and the protective resistance for 10 seconds of recovery is 3g.
It becomes necessary. However, unlike superconducting magnets, which are ``constant current sources'' that usually operate at extremely low voltage and high current,
This amount = 30g.

The constant resistance value of R=39 must be said to be rather excessive.

The superconducting magnet protection device of the present invention will be explained below.

FIG. 3 is a principle diagram showing an embodiment of the present invention, in which a switching device 1 and a mechanical load 8 are provided in place of the protective resistor SK in FIG. 1, and other symbols are the same parts as in FIG. 1. shows. The rotary machine 1 may be primarily a DC machine, or it may be an electric motor or a synchronous machine T' connected via a DC/AC converter lv, as shown in FIG.

Hereinafter, the turning machine 1 used in the present invention will be explained.

The rotating machine 1 performs mutual conversion between electrical energy and mechanical energy, and is structurally simple.
Since it is composed of an l1i1 trochanter and a stator, the - trochanter has a moment of inertia on the scale of a phase roar. and,
As is well known, this moment of inertia has %−
Rotational energy can be stored in the form of kinetic energy.

Next, the remarkable feature of the turning machine 1 is that the maximum torque is required at startup, which requires a large current.Normally, the load current increases from a standstill state to the rated speed. The relationship between the rotation speed and the rotation speed is bilinear as shown in FIG.

Such characteristics bring about an active effect not seen in conventional protective resistors. In other words, in FIG. 113 or FIG. When 2f is opened, an electromotive force is generated in the reverse wall as described above, but even if this electromotive force is applied to the rotating machine 7 via the diode 4, the rotor is closed at that point, so the The impedance of the turning point T is only the winding resistance, and #tW A 1 is almost a short circuit. .

This is generally three orders of magnitude smaller than the conventional holding resistor, so it not only does not generate an excessive voltage at the moment the switch s2 is opened, but also prevents large starting torque from being applied to the rotor of the switching machine 1. and K.

In this way, the superconducting magnet svc normal conduction transition is detected,
When the switch 2 is opened, a large current flows through the field element of the rotating machine T, and at the same time, the eight trochanters start rotating. On this occasion,
5K as shown in Figure 5 above.

- Since the turning machine 1 has a general Km turning speed port and the load current #lI in an inversely proportional relationship, it is characterized by a large current at the time of starting, so the starting current can be taken as the current value flowing through the superconducting magnet 3. KjlK is true. Furthermore, the stored energy in the form of rotational energy of the H trochanter can be quickly replaced with mechanical energy by this Tenryu flK. Moreover, the rotational energy is proportional to the square of the rotational speed, and as the rotational speed increases, the rotational energy of the rotating machine 1. Since the internal impedance of K increases, the load current decreases and is preferable.
Since the magnetic energy emitted from the superconducting magnet 3 also decreases, the rotating machine 1 will not run out of control.

In Figure 2, the solid line ■ is the number of the rotary machine T or single-pole machine (DC machine),
The solid line 11 indicates the generated voltage of the DC motor number of the rotating machine 1. As can be understood from this figure, if the rotating machine 1 is used as a protection device, the generated voltage can be reduced to a certain value or less.

Since the energy harvested by the conventional S-holding resistor is a pure resistance component, the current flowing out of the superconducting magnet 3 and the generated voltage are in phase, and a high voltage is directly generated. 3. Since the flowing current can be converted into the moment of inertia of the rotor system as transduction energy, this is a must because the phase of the voltage can be delayed and reduced compared to the current.

Another advantage of the invention is that rotational energy can be converted to other useful energies such as electrical, mechanical, chemical and thermal energy by feeding various loads. It can be seen from the above that it also has features that conventional protection functions do not have.

・As shown in Fig. 4, AC machine 1 is used as Kli turning point 1.
’ is used. The magnetic energy of the superconducting magnet 3 is not only converted into batten energy, but also converted into alternating current from the superconducting magnet 3 via a DC/AC converter. It is also possible to effectively extract the magnetic energy of .

The time constant for energy recovery must be determined in consideration of the mechanical strength, electrical insulation strength, thermal characteristics, etc. of the superconducting magnet 3, or the mechanical time constant of the rotating machine 1 must be proportional to the moment of inertia of the rotor. Since it is clear that the moment of inertia is insufficient with the rotor alone, by connecting the rotor with a moment of inertia (with a suitable flywheel effect), it is possible to obtain an energy profile with the desired time constant. Become.

In Fig. 6, the stored energy of the superconducting magnet 3 is transferred by a switch 2.10 controlled by a voltage detector 6.When a normal conduction transition is detected, the switch 2 is opened and at the same time the switch 10 is opened. It is controlled to close. In the embodiment shown in Fig. 6, since the switch 2゜100 operation timing can be set arbitrarily, K can also be used when manually stopping the excitation of the superconducting magnet 3. In addition, since the superconducting magnet storage device of the present invention uses the -transfer as a load for releasing stored energy, it is possible to prevent abnormally high voltage from being generated when a normal conduction transition occurs. , since it is possible to convert the stored energy into the form of relaxation energy as quickly as possible,
This has the great advantage of being able to effectively prevent equipment including superconducting magnets from burning out and breaking, as well as allowing for effective use of energy.

[Brief explanation of the drawing]

Fig. 111 is a principle diagram of a conventional superconducting magnet's holding path, Fig. ** is a diagram showing the relationship between the generated voltage and time constant of a superconducting magnet, and Fig. 111 is a diagram of the original superconducting magnet showing an embodiment of the present invention. 4 and 6 are principle diagrams showing other embodiments of the present invention, and 5WA is a diagram showing the relationship between the rotational speed of the single-turning machine and the load current. In the figure, 1 is a power supply, 2,1 is a -closer, 3 is a superconducting magnet,
4 is a diode, S is a resistor, 6 is a voltage detector, T
1, 3, 4, 1, 3, 4, 1, 2, 3, 4, 5, 1, 2, 3, 3, 4

Claims (3)

[Claims] (1) A superconducting magnet stabilizing device, characterized in that the superconducting magnet is supplied with a co-rotating machine for releasing stored energy when a normal conduction transition is detected in the superconducting magnet. (2) Claim l characterized in that the rotating machine is connected to an electrical or mechanical load! Iris (superconducting magnet image layer device according to item 11). (3) Claim No. 1 characterized in that the rotating machine is an AC machine connected via a DC/AC converter.
) The superconducting magnet retaining device described in item 2.