JPS6018179B2 - Rectifier flux pump device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a rectifying flux pump device.

A superconducting magnet is kept at an extremely low temperature, close to the helium liquefaction temperature, so that the coil has zero resistance, and a persistent current flows through the coil. Initially, a large current of several thousand amperes must be passed through the coil.

In the case of this charging, introducing the above-mentioned large current into the magnet coil from outside the cryogenic chamber through a large lead-in wire will introduce external heat into the cryogenic chamber, so it is necessary to insert the power transformer into the cryogenic chamber. You may need to charge the battery. One such method is a control system for a rectifying flux pump, in which a superconducting switch is inserted at the end of the secondary winding of the transformer, and the on/off of this superconducting switch is appropriately controlled to control the secondary winding. The idea is to cumulatively increase the charging current of a magnetic coil whose one end is connected to the neutral point of the wire. In order to facilitate understanding of the present invention, a conventional charging method using the rectifying flux pump device will be explained with reference to FIGS. 1 and 2. In FIG. 1, a transformer 1 has a primary winding 2 and a secondary winding 3 having a neutral point.
and has. It is assumed that these windings 2 and 3 are each wound with superconducting wire. One end of the magnet coil 4 to be charged is connected to the neutral point of the secondary winding 3, and each end of the secondary winding is connected to the above through the superconducting switches 5, 6 and current reversal detection circuits 7, 8, respectively. Connect to the other end of the magnet coil 4. A voltage waveform controller 9 is connected to the primary winding 2 of the transformer 1.
will be established. The voltage waveform controller 9 is configured to preprogram the waveform to be generated and generate a voltage based on it. Further, this detection signal is applied to the voltage waveform controller 9 so that a part of the waveform of the voltage applied to the transformer 1 can be modified in accordance with the detection signal generated when the current reversal detection circuits 7 and 8 detect a current reversal. . The superconducting switches 5 and 6 are controlled by a voltage waveform controller 9, but are also partially controlled by detection signals from current reversal detection circuits 7 and 8.

Now, turn off the switch 6, turn on the switch 5, and apply a positive pulse to the end of the primary winding 2 (10E in Fig. 2A, in the direction of the arrow 10).
, the magnet coil 4 is charged in the direction of the arrow 12 by the voltage induced in the secondary winding 3 in the direction of the arrow 11.

To explain the operation, it is assumed that the switch 5 is on and the switch 6 is off as before, and a voltage of 10E is applied to the transformer ZI secondary winding 2 at point a in FIG. At that time, an induced voltage +Q of waveform B proportional to 10E is generated in the secondary winding 3, and a current of waveform C flows in the primary winding 2. This induced voltage +Q is constant, and therefore, as shown by waveform D, the charging current in direction 11 in FIG. 1 increases at a constant rate. Next, when waveform A is made zero at point b, the primary current (waveform C) maintains a constant value, so the secondary induced voltage waveform B becomes zero, and the second! The current flowing through the magnet coil 4 in the figure also becomes constant (waveform D).

2 At this point b, switch 6 in Figure 1 is turned on, but since this switch 6 is a superconducting switch, it takes time (between b and c) to transition from normal conductivity to superconductivity.
When the switch 6 becomes superconducting at point C, a primary voltage of -E2 is applied (waveform A).

In this case, the primary current decreases at a constant rate during the period c-d (FIG. 2C), but the induced voltage -Q2 is maintained at a constant value (FIG. 2B). During this period, since the switches 5 and 6 in FIG. 1 are still in the on state, a short circuit current flows in the direction 13 opposite to the direction 12, so the current flowing through the switch 5 passes the zero point, and current reversal is detected. When the current in the circuit 7 is reversed, this detection signal is given to the voltage waveform controller 9 and the switch 5, and the primary voltage is made zero at point d (waveform A) in FIG. 2, and at the same time, the switch 5 is turned off. . At this time, the charging current in the direction 12 is transferred to the circuit including the switch 6 as a current in the direction 14. (The time between d and e is the transition time from superconductivity to normal conductivity of switch 5.) In the circuit including this switch 6, at point e in FIG.
, the charging current in the direction 14 continues to increase at a constant rate, and the charging current is accumulated in the magnet coil 4 (waveform D).

By repeating this operation, a certain value of current can be reached. However, when it is necessary to rapidly increase the charging current to the magnet coil, depending on the request, the critical current of the superconducting wire used in the primary winding of the transformer may be induced in the secondary winding due to the magnetic field characteristics. There was a limit to the current available, and the requirements could not be met.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rectifying flux pump device that can eliminate the above-mentioned drawbacks and increase the charging current to the magnet coil per unit time.

The present invention attempts to increase the charging current by using two transformers and applying a voltage to the magnet coil so that the respective secondary voltages are applied with the same polarity. Hereinafter, typical embodiments of the present invention will be described using the drawings.

The rectifying flux pump device 11 according to the present invention has a third
As shown in the figure, the first and second transformers 12, 13 and the respective secondary windings h4, 1 of these transformers 12, 13
5, superconducting switches 17 and 18 connected to both ends of the secondary winding 14 of the first transformer 12, and these superconducting switches 17 and 18. current reversal detection circuits 19 and 20 connected in series to both ends of the secondary winding 15 of the second transformer 13, and the primary windings of the first and second transformers 12 and 13, respectively; The voltage waveform controller 23 controls the waveform of the voltage to be applied to the lines 21 and 22. Next, the operation will be explained with reference to FIGS. 3 and 4.

A voltage corresponding to the solid line of the primary applied voltage A shown in FIG. 4 is applied from the voltage waveform controller 23 to the 15th winding 21 of the first transformer 12, and 22 is applied with a voltage indicated by a chain line of the primary applied voltage A shown in FIG. 4, which differs only in polarity from the above voltage. As a result, the first and second
The voltages induced in the secondary windings 14, 15 of the transformers 12, 013 are in the directions of arrows 24, 25, and a voltage shown as secondary induced composite voltage B in FIG. 4 is applied to the magnet coil 16. First, when the superconducting switch 17 is off and the superconducting switch 18 is on, the voltage waveform controller 23 supplies the first transformer 12 with a voltage of 10E as shown in FIG. 4, and the second transformer 13 with a voltage of -E. , the secondary sides of the respective transformers 12 and 13 generate voltages +Q, , -Q, and a voltage of 12Q is applied to the magnet coil 16. Charging current flows in the direction of arrow 26 in the figure.

This charging current increases as shown in the charging current waveform D shown between a and b in FIG. 4, but the increase is twice that of the conventional rectifying flux pump device. Next, at point b in FIG. 4, the voltage applied to the transformers 12 and 13 is reduced to zero, and at the same time, the superconducting switch 17 is turned on. The period between b and c in FIG. 4 is the time during which the superconducting switch 17 transitions from normal conductivity to superconductivity, and during this period, the charging current flowing through the magnet coil 16 is also constant. Next, at point c in FIG. 4, voltages -E2 and -E2 are applied from the voltage waveform controller 23 to the transformers 12 and 13, respectively. At this time, the voltages generated on the secondary sides of the transformers 12 and 13 are -Q2, +Q2, the voltage applied to the magnet coil 16 is -2Q2, and the direction of the current is the direction of the arrow 27 opposite to the direction of the arrow 26. The direction will be Superconducting switch 18
When the direction of the current flowing in is reversed, the current reversal detection circuit 2
Detected at 0. This detection signal is sent to the voltage waveform controller 23 and the superconducting switch 18, and at point d in FIG. 4, the voltage applied to the transformers 12 and 13 is made zero, and at the same time, the superconducting switch 18 is turned off. At this time, the current is arrow 28
is moving in the direction. The period between d and e in FIG. 4 is the time during which the superconducting switch 18 is transitioning from superconductivity to normal conductivity. Next, when the voltage waveform controller 23 applies voltages 1E and 10E to the transformers 12 and 13, respectively, the magnet coil 1
2 of Atsushi-2 is applied to 6, and the charging current of the magnet coil 16 flows in the direction of arrow 28 and is accumulated. By repeating the above operations, it is possible to cause the magnet coil 16 to reach a desired value of current. As is clear from the above explanation, two transformers are used to apply twice the voltage to the magnet coil 16 compared to the following rectifying flux pump device, so the desired charging current can be increased in a short time. can be increased up to a value of

In addition, when performing discharge, the above-mentioned procedure may be performed in reverse.
In the above description, two transformers that generate the same value of secondary induced voltage are used, but transformers that generate secondary induced voltage of different values may be used. As is clear from the above description, when the rectifying flux pump device according to the present invention is used, the amount that can be charged to the magnet coil per unit time can be greatly increased compared to the conventional one.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional rectifying flux pump device.
FIG. 2 is a timing chart for explaining its operation, FIG. 3 is a schematic diagram of the rectifying flux pump device according to the present invention, and FIG. 4 is a timing chart for explaining its operation. 12,13...Transformer, 14,15...
・Secondary winding, 16... Magnet coil, 17, 18...
...Superconducting switch, 19, 20...Current reversal detection circuit 0 circuit, 23...Voltage waveform controller. Figure 1 Figure 3 Figure 2 Figure 4

Claims (1)

[Claims] 1 A magnet connected between the first and second transformers, the neutral point of the secondary winding of the first transformer, and the neutral point of the secondary winding of the second transformer. a superconducting switch connected to both ends of the secondary winding of the first transformer, and a superconducting switch connected in series with these superconducting switches to both ends of the secondary winding of the second transformer. The current reversal detection circuits and the superconducting switches connected to each other are controlled to turn on and off, the voltage waveforms applied to the first and second transformers are controlled, and the voltage waveforms applied to the magnet coils are controlled to turn on and off. 1
, and a voltage waveform controller that performs control such that the secondary induced voltages of the respective second transformers are applied with the same polarity.