JPS6331091B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power supply control device for a superconducting device, and particularly to a normal conduction transition (hereinafter referred to as transition) of a superconductor.
The present invention relates to a power supply control device that controls current flow to a superconducting device while preventing such problems from occurring.

When a superconducting device is energized, if a transition occurs in a part of the conductor for some reason and the transition region expands without recovering to the superconducting state, fluid loss due to the finite resistance generated within the conductor occurs. There is a risk of damage to equipment (conductors, containers, etc.) due to boiling of helium. Conventionally, it has been considered to protect the conductor by consuming energy within the superconducting device outside the device in order to prevent such transitions.

However, with the above-mentioned methods, operation cannot be expected until after the superconducting device has transferred, so methods have recently been considered to prevent the transfer by detecting phenomena that precede the transfer. However, conventional control devices only stop or cut off the energization after transition or when transition is predicted, and have the disadvantage that they cannot meet the demand for energization control in a predetermined pattern.

The present invention was invented in view of the above points, and its purpose is to prevent the transition of a superconducting device and to minimize the deviation between a predetermined energizing current pattern and an actual energizing current pattern. The purpose of the present invention is to provide a power supply control device for the device.

The causes of transitions in superconductors are thought to be electromagnetic and mechanical, and are caused by shunt phenomena, eddy currents, and magnetization due to the movement of magnetic flux in the conductor and the movement (deformation) of the conductor. It is said that heat is generated in the conductor, ultimately causing the temperature of the conductor to rise.

The present invention focuses on the above points and provides (1) a detector for temperature rise in a conductor, (2) a detector for bubbles in liquid helium, (3) a detector for sound waves generated by the movement of a conductor, and (4) a detector for a conductor. conductor speed detector to determine the electric field generated by the movement of the conductor (5); magnetic field detector to determine the eddy current loss generated in the conductor, etc.; The purpose of this method is to perform control, find the deviation of the actual current flow pattern from a predetermined current flow pattern, and realize control that minimizes the deviation within a range where transition does not occur.

FIG. 1 shows an embodiment of the present invention.
The superconducting coil 10 is placed in a container 11 and is cooled by liquid helium 13 produced by a liquefier 12 .

The superconducting coil 10 is energized by a power supply 20, and the power supply 20 receives a control signal 31 from a power supply control device 30.
Its output is controlled by

Various detectors for detecting phenomena that cause the transition of the superconducting coil 10 are installed in the superconducting coil 10 or the container 11. The detectors include a bubble detector 40 that detects bubbles generated in liquid helium 13, a sonic detector 50 that captures sound waves generated by strain inside the superconductor and movement of the conductor, and a sonic detector 50 that detects sound waves generated by strain inside the superconductor and movement of the conductor. A speed detector 60, a magnetic detector 70, etc. are used to determine the electric field generated in the magnetic field.
Of these, the magnetic detector 70 is also used to determine the eddy current loss generated in the conductor.

These detector signal values are the physical quantities that cause the transition (the amount of bubbles, the size of the electric field generated within the conductor, etc.)
corresponds to When the physical quantity that causes the transition exceeds a threshold value, a rapid transition occurs in the superconducting device.

Therefore, in order to prevent transitions that occur while energizing a superconductor, one or a combination of these detector signals must reach a preset alarm level for each of them. In such a case, the power source may be controlled to reduce the current flow to reduce the amount that causes the transfer.

The above will be explained using FIG. The horizontal axis is time;
The vertical axis represents a physical quantity (for example, the amount of bubbles in liquid helium) corresponding to the cause of the transition. Assume that a transition occurs for some reason at time _t1 . When this transition increases and exceeds the threshold L _T at time t ₃ , the transition spreads throughout the superconductor, posing a danger to the device (curve A in the figure).
In order to avoid this, the alarm level L _A is set lower than L _T , and if the physical quantity exceeds L _A at time t ₂ , the current flowing through the device is reduced. The physical quantity can prevent the growth of metastasis without reaching L _T (curve B in the same figure). The effect of the time delay between detecting the transition at time _t2 and actually reducing the applied current (such as reaching L _T before the transition begins to disappear) can be avoided by setting the alarm level low. This can be resolved by doing so.

FIG. 3 is a diagram showing the temporal correlation of detector signals such as the current of the superconducting device and changes in physical quantities corresponding to causes of transition.

The current setting pattern given to the power supply control device in advance is A. Assume that while the superconducting device is being energized according to this current setting pattern A, a transition occurs at time _t4 , the corresponding physical quantity C increases, and exceeds the alarm level _LA at time _t5 . At this time, the detector outputs a detector signal D, and the power supply control device sends the power supply a time signal so that the deviation from the current setting pattern A is always minimized within the range where the physical quantity corresponding to the cause of the transition does not exceed L _A. A control signal is sent between t ₅ and _{t 6} , and if the transition disappears at time t ₆ , the power supply control device instructs the power supply to immediately return to the original set current pattern A, and as a result, the solid line The current pattern is obtained.

These functions of power control equipment include analog,
It can be easily implemented using any digital circuit type.

As described above, it is possible to obtain a power supply control device for a superconducting device that minimizes deviation from a predetermined set current pattern while preventing transition.

Furthermore, the method of controlling the superconducting device so that the integral value of the deviation between the actual current pattern and the set current pattern becomes zero is to Just make it bigger. The method will be explained according to FIG. The diagram is the same as Figure 3 until time t ₆ , but after the cause of the transition that occurred at time t ₄ disappears at time t ₆ , the set current pattern A It allows more current to flow. Naturally, if the physical quantity C' corresponding to the cause of transition due to the increase in current (due to heat generation in the conductor, etc.) exceeds the alarm level L _A , a new detector signal D' due to the increase in current is generated, so the power supply control device suppresses the power output to prevent metastasis from occurring. This current increase continues until time _t7 , when the integral value of the deviation due to the set current pattern, which occurs to avoid transition, is canceled out.

According to this embodiment, the integral value of the deviation with respect to the current setting pattern that occurs in order to avoid transition can be made zero, and the overall current value can be made to match that of the preset current pattern.

According to the present invention, transition of a superconducting device is prevented,
A power supply control device for a superconducting device that minimizes the deviation between a predetermined energizing galvanic current pattern and an actual energizing galvanic current pattern can be obtained, and can match the total current value of a preset current pattern, thereby achieving an optimal superconducting device. A fast and economical driving method will be established.

[Brief explanation of the drawing]

Fig. 1 is a diagram of a superconducting device to which the present invention is applied, Fig. 2 is a diagram showing changes in the amount that causes the transition that appears in the detector signal, and Fig. 3 is the relationship between the current of the superconducting device and the detector signal. FIG. 4 is the same as FIG. 3, but shows the case of control where the integral of the deviation is zero. 10... superconducting coil, 11... container, 12...
...Liquifier, 13...Liquid helium, 20...Power source, 30...Power control device, 31...Control signal,
40...Bubble detector, 50...Sound wave detector, 60
...Speed detector, 70...Magnetic detector.

Claims (1)

[Claims] 1 The power source is controlled so that a current is supplied according to a predetermined current pattern of the superconducting device, and when the signal from the detector that detects the sign of the normal conduction transition phenomenon of the superconducting device reaches an alarm level, In a power supply control device that controls the power supply so that a current is supplied to the superconducting device within a range where the conductive transition phenomenon does not occur and the deviation from the current pattern is minimal, from the time when the normal conductive transition phenomenon is suppressed. , in addition to the current according to the current pattern, the power supply is supplied with an amount of current approximately equal to the integral value of the deviation that occurs when the current decreases, and then the power supply is configured to supply the current according to the current pattern to the superconducting device. A power supply control device for a superconducting device characterized by having a control function.