JP2019175889A - Superconducting device and superconducting coil protection method - Google Patents

Abstract

To protect any superconducting coils among a plurality of superconducting coils connected in series.SOLUTION: A superconducting device 1 includes: a plurality of superconducting coils L connected in series; a first resistor and a first switch S that are connected in series with each other and provided in parallel with each of the superconducting coils L; and a control unit 12 that, when it is detected that quench has occurred at any of the superconducting coils L, makes one or more first switches S provided in parallel with one or more superconducting coils L other than a first superconducting coil L at which quench has occurred in a conduction state among the superconducting coils L.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a superconducting device and a superconducting coil protection method capable of protecting a superconducting coil in which a quench has occurred.

  Conventionally, there has been proposed a method for preventing the superconducting coil from being damaged when quenching occurs in the superconducting coil (see, for example, Non-Patent Document 1).

Ryuta Matsuo, Akane Kojima, Takahiro Ariyama, Naohiro Matsuda, Yoshiki Hamada, Tomoaki Takao, Shugo Tsukamoto “Proposal of Quench Protection Method for HTS Coils Consisting of Multi-Superconducting Coils”, 2017 Superconducting Equipment Research Group ASC-17-010

  In the conventional method, it is assumed that quenching occurs in the superconducting coils at both ends among the plurality of superconducting coils connected in series. However, it is also assumed that quenching occurs in superconducting coils other than the superconducting coils at both ends. The conventional method has a problem that when a quench occurs in a superconducting coil other than the superconducting coils at both ends, the superconducting coil in which the quench occurs cannot be protected.

  Therefore, the present invention has been made in view of these points, and an object thereof is to provide a superconducting device and a superconducting coil protection method for protecting an arbitrary superconducting coil among a plurality of superconducting coils connected in series. To do.

  A superconducting device according to a first aspect of the present invention includes a plurality of superconducting coils connected in series, a first resistor and a first switch connected in series with each other and provided in parallel with each of the plurality of superconducting coils. And when one of the plurality of superconducting coils detects that quenching has occurred, the plurality of superconducting coils are provided in parallel with one or more superconducting coils other than the first superconducting coil in which quenching has occurred. And a control unit that brings one or more first switches into a conductive state.

  The superconducting device includes a connection point between two superconducting coils adjacent to each other among the plurality of superconducting coils, and a connection point between the two first resistors and the first switch group corresponding to the two superconducting coils. You may further have the 2nd resistor and 2nd switch which were provided in series between.

  The control unit includes a first switch provided in parallel with the first superconducting coil, and a first position symmetrical to the position of the first superconducting coil with respect to a central position in a serial connection direction of the plurality of superconducting coils. The one or more first switches other than the first switch provided in parallel with the two superconducting coils may be in a conductive state.

  The control unit may turn on the one or more first switches provided in parallel with all the superconducting coils other than the first superconducting coil and the second superconducting coil among the plurality of superconducting coils. .

  Of the plurality of superconducting coils, the resistance value of the first resistor provided in parallel with the superconducting coil may be smaller as it is closer to the center position in the series connection direction of the plurality of superconducting coils.

  Moreover, it may further include a second resistor provided in parallel with the plurality of superconducting coils, and a resistance value of the first resistor may be smaller than a resistance value of the second resistor. In this case, the total value of the resistance values of the one or more first resistors connected in series with the one or more first switches to be in a conductive state may be smaller than the resistance value of the second resistor.

  The superconducting device has the plurality of first resistors provided in parallel with the plurality of superconducting coils, each having a different resistance value, and the control unit is the superconducting coil in which the quench has occurred. The first resistor to be turned on among the plurality of first resistors may be determined.

  The superconducting coil protection method according to the second aspect of the present invention includes a plurality of superconducting coils connected in series, a first resistor connected in series with each other and provided in parallel with each of the plurality of superconducting coils, and A method of controlling a device having a first switch, the step of detecting that quenching has occurred in any of the plurality of superconducting coils, and the occurrence of quenching in any of the plurality of superconducting coils. Detecting one of the first switches provided in parallel with one or more superconducting coils other than the first superconducting coil in which quenching occurs among the plurality of superconducting coils, Have.

  According to the present invention, it is possible to protect an arbitrary superconducting coil among a plurality of superconducting coils connected in series.

It is a figure which shows the outline | summary of the superconducting coil unit which a superconducting apparatus has. It is a figure which shows the structure of a superconducting apparatus. It is a simulation result which shows the change of the electric current which flows through each superconducting coil, after quenching generate | occur | produces in some superconducting coils. It is a simulation result which shows the change of the electric current which flows through each superconducting coil, after quenching generate | occur | produces in some superconducting coils. It is a figure which shows the structure of the superconducting apparatus which concerns on 2nd Embodiment.

<First Embodiment>
[Overview of superconducting coil]
FIG. 1 is a diagram showing an outline of a superconducting coil unit 11 included in the superconducting device 1 of the present embodiment. FIG. 2 is a diagram showing the configuration of the superconducting device 1. The superconducting device 1 is, for example, an MRI (Magnetic Resonance Imaging) device.

  The superconducting coil unit 11 shown in FIG. 1 includes superconducting coils L1, L2, L3, and L4, which are four pancake coils, but the number of superconducting coils included in the superconducting coil unit 11 is arbitrary. When a current is passed through the superconducting coils L1, L2, L3, and L4, a magnetic field is generated as shown in FIG.

  If a quench occurs in any of the superconducting coils L1, L2, L3, and L4, the superconducting coil in which the quench has occurred is damaged. Therefore, when the superconducting device 1 detects that the quench has occurred, the superconducting device 1 protects the superconducting coil in which the quench has occurred by performing a commutation that transfers the current flowing in the superconducting coil in which the quench has occurred to another superconducting coil. It has a configuration. Details of the superconducting device 1 will be described below.

[Configuration of Superconducting Device 1]
The superconducting device 1 includes a superconducting coil unit 11 and a control unit 12. The superconducting coil unit 11 includes a current source P, a plurality of superconducting coils L (superconducting coils L1 to Ln), a plurality of first resistors R1 (resistors R11 to R1n), and a plurality of second resistors R2 (resistors). R21 to R2n), a plurality of first switches S1 (switches S11 to S1n), a plurality of second switches S2 (switches S21 to S2n), a third switch T, a diode D, a third resistor r, Have Here, n is an integer of 2 or more.

  The current source P and the third switch T are provided in series with the plurality of superconducting coils L. The current source P supplies a current for generating a magnetic field in the plurality of superconducting coils L. The third switch T is connected in series with the current source P, and based on the control of the control unit 12, a conduction state in which the current output from the current source P flows to the plurality of superconducting coils L, and the current to the plurality of superconducting coils. The non-conducting state which does not flow through L is switched.

  The diode D and the third resistor r are provided in parallel with a plurality of superconducting coils L connected in series with each other. The diode D and the third resistor r are connected in series between the side of the current source P not connected to the third switch T and the side of the third switch T not connected to the current source P. ing.

  The superconducting device 1 includes first resistors R11 to R1n and first switches S11 to S1n connected in series with each superconducting coil L in parallel. That is, the superconducting device 1 includes first resistors R11 to R1n and first switches S11 to S1n that are connected in series with each other and provided in parallel with each of the plurality of superconducting coils L1 to Ln.

  The superconducting device 1 includes a second resistor R21 connected in series between a connection point between adjacent superconducting coils L and a connection point between the first resistor R1k and the first switch S1 (k + 1). To R2n and second switches S21 to S2n. Here, k is an integer of n or less. The resistance values of the first resistors R11 to R1n are smaller than the resistance value of the third resistor r. The first switches S11 to S1n, the second switches S21 to S2n, and the third switch T can be switched between a conduction state and a non-conduction state under the control of the control unit 12.

  The control unit 12 is a computer, for example. The control unit 12 controls a conduction state of the plurality of first switches S11 to S1n, the second switches S21 to S2n, and the third switch T by executing a program stored in the recording medium.

  When the control unit 12 detects that quenching has occurred in any of the plurality of superconducting coils L, the control unit 12 brings the third switch T into a non-conductive state. Moreover, the control part 12 makes one or more 1st switch S1 provided in parallel with one or more superconducting coils L other than the 1st superconducting coil L which the quench generate | occur | produced among the some superconducting coils L into a conduction | electrical_connection state. Moreover, the control part 12 makes at least one part 2nd switch S2 into a conduction | electrical_connection state so that an electric current may flow into 1st resistor R1 connected in series with 1st switch S1 made into the conduction | electrical_connection state. For example, when the control unit 12 detects that quenching has occurred in the superconducting coil L1 and the superconducting coil Ln, the first switches S12 to S1 (n) provided in parallel with the superconducting coils L2 to L (n−1). -1) is turned on, and the second switches S21 to S2 (n-1) are turned on.

  When the control part 12 makes the 3rd switch T a non-conduction state, the electric current supplied from the current source P does not flow into the superconducting coils L1 to Ln. And while the control part 12 makes at least any one of 1st switch S12-S1 (n-1) a conduction | electrical_connection state, an electric current is sent to 1st resistor R1 connected in series with 1st switch S1 made into the conduction | electrical_connection state. By making it flow, the current corresponding to the current flowing in the superconducting coil L1 and the superconducting coil Ln due to magnetic coupling due to mutual inductance causes the superconducting coil L (for example, superconducting coil) corresponding to the first switch S in the conductive state. The current flowing through the superconducting coil L1 and the superconducting coil Ln is rapidly reduced by commutation to the coil L2 to the superconducting coil L (n-1)). As described above, the current flowing in the superconducting coil L1 and the superconducting coil Ln is rapidly reduced, thereby suppressing the generation of Joule heat in the superconducting coil L1 and the superconducting coil Ln that are in the normal conducting state due to the quench. Therefore, damage to the superconducting coil L1 and the superconducting coil Ln can be prevented.

  The control unit 12 is symmetrical to the position of the superconducting coil L where the quench has occurred with reference to the first switch S1 provided in parallel with the superconducting coil L where the quench has occurred and the center position in the series connection direction of the plurality of superconducting coils L. One or more first switches S1 other than the first switch S1 provided in parallel with the second superconducting coil L at any position may be in a conductive state. For example, the control unit 12 brings one or more first switches S1 provided in parallel with all the superconducting coils other than the first superconducting coil and the second superconducting coil among the plurality of superconducting coils L into a conductive state.

  For example, when quenching occurs in the superconducting coil L1, the control unit 12 (1) a first switch S11 provided in parallel with the superconducting coil L1, and (2) a superconducting coil corresponding to the central position of the plurality of superconducting coils L. First switches S12 to S1 (n-1) other than the two first switches S1 of the first switch S1n provided in parallel with the superconducting coil Ln at a position symmetrical to the superconducting coil L1 with reference to L (n / 2). ) Is turned on. Moreover, the control part 12 makes 2nd switch S21-S2 (n-1) a conduction state.

  For example, when quenching occurs in the superconducting coil L2, the control unit 12 is provided in parallel with (1) the first switch S2 provided in parallel with the superconducting coil L2, and (2) with the superconducting coil L (n-1). The first switch S1 and the first switches S2 to S (n-2) other than the two first switches of the first switch S (n-1) are turned on. Moreover, the control part 12 makes 2nd switch S21-S2 (n-1) a conduction state. By doing so, it is possible to prevent the superconducting coil L from being damaged due to current imbalance.

  The resistance values of the plurality of first resistors R11 to R1n are arbitrary, but the resistance values of the first resistors R11 to R1n are preferably smaller than the resistance value of the third resistor r. The total resistance value of the one or more first resistors R1 connected in series with the one or more first switches S1 to be in a conductive state is preferably smaller than the resistance value of the third resistor r. As described above, when the resistance value of each of the first resistors R11 to R1n is smaller than the resistance value of the third resistor r, no quench occurs when any of the superconducting coils L is quenched. The current value commutated to the superconducting coil L can be sufficiently increased.

  Further, among the plurality of superconducting coils L, the resistance value of the first resistor R1 provided in parallel with the superconducting coil L is decreased as the position is closer to the center position in the series connection direction of the plurality of superconducting coils L. Also good. By doing in this way, it is easy for current to flow to the superconducting coil L where the distance from the superconducting coil L1 or the superconducting coil Ln at both ends where quenching is likely to occur is large and the mutual inductance between the superconducting coil L1 or the superconducting coil Ln is small. Become. As a result, the difference in the amount of current flowing through each of the plurality of superconducting coils L can be reduced, and the current flowing through the superconducting coil L in which quenching has occurred can be reduced in a short time.

[simulation result]
3 and 4 are simulation results showing changes in the current flowing through each superconducting coil L after quenching occurs in some superconducting coils L. FIG. The horizontal axis of FIGS. 3 and 4 represents the elapsed time since the quenching occurred, and the vertical axis represents the magnitude of the current flowing through one superconducting coil L. The simulation results shown in FIGS. 3 and 4 are simulation results when the superconducting device 1 has eight superconducting coils L (that is, when n = 8).

  FIG. 3 shows currents flowing through the superconducting coils L1 and L8, the superconducting coils L2 and L7, the superconducting coils L3 and L6, and the superconducting coils L4 and L5 when quenching occurs in the superconducting coil L1 and the superconducting coil L8. . The current flowing through the superconducting coil L1 and the superconducting coil L8 decreases rapidly immediately after the quench occurs, and the current flowing through the superconducting coil L2 and the superconducting coil L7 increases. Thereafter, as the current flowing through the superconducting coil L3 and the superconducting coil L6, and the superconducting coil L4 and the superconducting coil L5 increase, the current flowing through the superconducting coil L2 and the superconducting coil L7 also decreases. Thus, it was confirmed that the current flowing through the superconducting coil L1 and the superconducting coil L8 was commutated to the inner coil, thereby preventing the superconducting coil L1 and the superconducting coil L8 from being damaged.

  FIG. 4 shows the current flowing through each superconducting coil L when quenching occurs in the superconducting coil L2. The current flowing through the superconducting coil L2 decreases rapidly immediately after the quench occurs, and the current flowing through the superconducting coil L1 and the superconducting coil L3 adjacent to the superconducting coil L2 increases. Thereafter, as the current flowing through the other superconducting coil L increases, it can be confirmed that the current flowing through the superconducting coil L1 and the superconducting coil L3 also decreases. Thus, even when quenching occurred in the superconducting coil L other than both ends, commutation occurred, and it was confirmed that damage to the superconducting coil L in which quenching occurred could be prevented.

[Effects of superconducting device 1]
As described above, in the superconducting device 1, the first resistor R and the first switch S are provided in parallel with each superconducting coil L. And when the control part 12 detects that quench generate | occur | produced in either of the several superconducting coils L, one or more superconducting coils L other than the superconducting coil L which the quench generate | occur | produced among several superconducting coils L and One or more first switches S provided in parallel are turned on. By doing in this way, since the current flowing through the superconducting coil L where the quench has occurred is transferred to the superconducting coil L in a position parallel to the first switch S in the conducting state, the superconducting coil where the quench has occurred The current flowing through L is reduced, and damage to the superconducting coil L in which quenching has occurred can be prevented.

  In addition, in the above description, although the control part 12 showed the operation example which makes 2nd switch S21-S2 (n-1) a conduction | electrical_connection state, the control part 12 other than the superconducting coil L in which quench generate | occur | produced was shown. The second switch S2 may partially be in a conductive state so that current flows through one or more first resistors R1 provided in parallel with the one or more superconducting coils L. For example, when quenching occurs in the superconducting coil L1, the control unit 12 causes the first switch S12, the second switch S21, and the second switch S22 to be in a conductive state so that a current flows through the first resistor R21. Good. Further, the superconducting device 1 may not have the second switch S2.

<Second Embodiment>
FIG. 5 is a diagram showing a configuration of the superconducting device 2 according to the second embodiment. The superconducting device 2 includes a plurality of first resistors R and first switches S that are provided in parallel with the plurality of superconducting coils L and have different resistance values. The superconducting device 2 connects, for example, the first resistor R11 and the first resistor R31 provided in parallel with the superconducting coil L1, and the first resistor R11 and the first resistor R32 to the superconducting coil L1. A third switch S21 and a fourth switch S41.

  The control unit 12 includes a first resistor R1 and a first resistor that are turned on among the plurality of first resistors R1 and the plurality of first resistors R3, depending on which of the superconducting coils L in which the quench has occurred. Determine R3. For example, the closer the superconducting coil L in which quenching occurs, the greater the mutual inductance, so that the control unit 12 determines to make the smaller first resistor R1 or first resistor R3 conductive. Specifically, when the resistance value of the first resistor R11 is larger than the resistance value of the first resistor R31, when a quench occurs in the superconducting coil L2, the first resistor R11 is turned on, and the superconducting coil L3 When the quench occurs, the first resistor R31 is brought into a conducting state. By doing in this way, the dispersion | variation in the magnitude | size of the electric current which generate | occur | produces by commutation by the position of the superconducting coil L where quenching generate | occur | produced can be made small.

[Effects of superconducting device 2]
As described above, the control unit 12 of the superconducting device 2 has the first resistor R1 and the first resistor R3 provided in parallel with the other superconducting coils L depending on which of the superconducting coils L has been quenched. The resistance value can be controlled. Since the superconducting device 2 has such a configuration, the superconducting device 2 can control the current flowing through each superconducting coil L to a desired range regardless of the position of the superconducting coil L where the quench occurs. It becomes easy to prevent damage to other superconducting coils L together with the superconducting coil L where the quench has occurred.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment, A various deformation | transformation and change are possible within the range of the summary. is there. For example, the specific embodiments of device distribution / integration are not limited to the above-described embodiments, and all or a part of them may be configured to be functionally or physically distributed / integrated in arbitrary units. Can do. In addition, new embodiments generated by any combination of a plurality of embodiments are also included in the embodiments of the present invention. The effect of the new embodiment produced by the combination has the effect of the original embodiment.

DESCRIPTION OF SYMBOLS 1 Superconducting device 2 Superconducting device 11 Superconducting coil unit 12 Control part L1-Ln Superconducting coil R11-R1n, R31, R32 1st resistor R21-R2n 2nd resistor r 3rd resistor S11-S1n 1st switch S21-S2n Second switch T Third switch P Current source D Diode

Claims (9)

A plurality of superconducting coils connected in series;
A first resistor and a first switch connected in series with each other and provided in parallel with each of the plurality of superconducting coils;
One or more provided in parallel with one or more superconducting coils other than the first superconducting coil in which quenching occurred among the plurality of superconducting coils when it is detected that quenching has occurred in any of the plurality of superconducting coils. A control unit for turning on the first switch of
A superconducting device. Between the connection point of two superconducting coils adjacent to each other among the plurality of superconducting coils and the connection point of the two first resistors and the first switch group corresponding to the two superconducting coils in series. A second resistor and a second switch provided;
The superconducting device according to claim 1. The control unit includes a first switch provided in parallel with the first superconducting coil, and a first position symmetrical to the position of the first superconducting coil with respect to a central position in a serial connection direction of the plurality of superconducting coils. 2 bringing the one or more first switches other than the first switch provided in parallel with the superconducting coil into a conductive state;
The superconducting device according to claim 1 or 2. The control unit makes the one or more first switches provided in parallel with all the superconducting coils other than the first superconducting coil and the second superconducting coil among the plurality of superconducting coils,
The superconducting device according to claim 3. Among the plurality of superconducting coils, the closer to the center position in the series connection direction of the plurality of superconducting coils, the smaller the resistance value of the first resistor provided in parallel with the superconducting coil,
The superconducting device according to any one of claims 1 to 4. A second resistor provided in parallel with the plurality of superconducting coils;
A resistance value of the first resistor is smaller than a resistance value of the second resistor;
The superconducting device according to any one of claims 1 to 5. A total value of resistance values of the one or more first resistors connected in series with the one or more first switches to be in a conductive state is smaller than a resistance value of the second resistor;
The superconducting device according to claim 6. A plurality of first resistors provided in parallel with each of the plurality of superconducting coils, each having a different resistance value;
The control unit determines a first resistor to be in a conductive state among the plurality of first resistors depending on which of the superconducting coils in which a quench occurs.
The superconducting device according to any one of claims 1 to 7. A method for controlling a device having a plurality of superconducting coils connected in series and a first resistor and a first switch connected in series with each other and provided in parallel with each of the plurality of superconducting coils. ,
Detecting that a quench has occurred in any of the plurality of superconducting coils;
One or more provided in parallel with one or more superconducting coils other than the first superconducting coil in which quenching occurred among the plurality of superconducting coils when it is detected that quenching has occurred in any of the plurality of superconducting coils. Bringing the first switch of the device into a conductive state;
A method of protecting a superconducting coil.

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