CN103560483A - Excitation power supply for superconducting magnet, and operation method thereof - Google Patents

Abstract

An excitation power supply for a superconducting magnet is provided. The excitation power supply (101) includes: a power supply (1); a power unit (3); when an abnormality is detected in the superconducting magnet (2), the contact (4a) that short-circuits the two ends of the output of the power unit (3) is closed and A protection circuit (16) for making it in a protection state; and a first shunt resistor (5) for detecting the current value in the circuit A. The excitation power supply (101) also includes a reset circuit (31), after the protective relay (4) is activated by the protective circuit (16) to close the contact (4a), the first shunt resistor (5) and the second The detection value of the shunt resistance (8) makes the output current value of the power unit (3) consistent with the current value passing through the superconducting coil (2L), and then the contact (4a) is disconnected to restore from the protection state.

Description

Excitation power supply for superconducting magnet and method of operation thereof

This application is a divisional application of the invention patent application with the application number "201010536637.4". The application date of the invention patent with the application number "201010536637.4" is November 04, 2010, and the title of the invention is "excitation power supply for superconducting magnet and its operation method".

technical field

The present invention relates to field power supplies for superconducting magnets and methods of operation thereof.

Background technique

There is a so-called quench phenomenon in a superconducting magnet, that is, a phenomenon in which a voltage is generated due to the destruction of the superconducting state and zero resistance changes to a normal conductive state. High voltages will appear in superconducting magnets composed of superconducting coils. In addition, conversely, if the current changes rapidly due to a problem in the excitation power supply itself, it will interact with the occurrence of the above-mentioned quench. On the excitation power supply side, the power element may be damaged due to high voltage or large energy that has lost its destination due to reverse flow, and on the superconducting magnet side, the superconducting magnet may be damaged due to a quench due to a sudden change in current.

Therefore, when an abnormality is detected in any one of the excitation power supply and the superconducting magnet, it is an appropriate operation to disconnect (connect) each other. However, when a huge current flows, it is dangerous to cut off (cut off) the interconnection (connection). Here, in the technology described in Patent Document 1, for example, it is proposed to arrange capacitors in parallel with respect to circuit breakers.

Patent Document 1: Japanese Patent Application Publication "JP-A-7-177648"

Contents of the invention

However, the protection method of cutting off the contacts that are being energized is not suitable for large current control. In the protection method of large current control, generally, the method of short-circuiting the output both ends of an excitation power supply and substantially disconnecting this excitation power supply and a superconducting coil is used.

Here, there is a drawback in the method of short-circuiting both output ends of the field power supply. For example, if the superconducting coil is actually not quenched but is short-circuited (misoperation) due to false detection, it will cause a combination of small resistance (R) and superconducting coil (L), and the release of stored energy will take a long time, As a result, both ends of the output cannot be released from the short circuit state for a long time

In addition, as an abnormality (problem) occurring on the field power supply side, there is a so-called overheating abnormality caused by overheating of a power element. When the sequence controller or microcomputer in use detects a sudden drop in the main power supply voltage, it regards it as an internal abnormality and stops the current output. During the same period, the short-circuit state of the output cannot be released. In addition, even if it is assumed that UPS is used to solve the problem of voltage sag, however, because its backup time and backup range are restricted, that is, for example, it can only be maintained for 10 minutes, and it can only maintain the control system and cannot backup the power system. Therefore, it is still There is a problem that it is necessary to short-circuit the output terminals of the excitation power supply for a certain period of time to protect the magnet, and it is difficult to return to a normal state.

In addition, for example, when the fuse inside the field power supply is blown, the fuse blown problem can be solved by simply replacing the fuse. However, as described above, it takes a long time to restore a superconducting magnet without quenching from a protected state to a normal state.

On the other hand, from the viewpoint of preventing damage to the excitation power supply and the superconducting magnet, it is an ideal choice to improve the detection level of abnormal states such as quenching. In addition, from the viewpoint of avoiding malfunctions of the sequence controller or the microcomputer, it is desirable to increase the detection sensitivity to voltage dips. However, if the level of detection of abnormal states is increased, the frequency of occurrence of malfunctions will increase (tradeoff problem).

The present invention has been made in view of the above-mentioned problems, and its object is to provide an excitation power supply for a superconducting magnet and an operation method thereof, that is, even if abnormal conditions such as quench, internal abnormality, and main power supply voltage dip are A short circuit occurs at both ends of the output of the excitation power supply due to false detection, or, for example, when the main power supply fails or an abnormality occurs when the fuse inside the excitation power supply is replaced, it is necessary to deal with the abnormal situation and reset it by taking measures such as restoring power supply or replacing the fuse An excitation power supply for a superconducting magnet capable of quickly returning to a normal state (non-short-circuit state) after being in a normal state and an operating method thereof.

In order to achieve the above object, the present invention provides an excitation power supply for a superconducting magnet that excites a superconducting magnet equipped with a superconducting coil, which is characterized in that it includes: a power supply; a power unit connected to the power supply; a protection device, When an abnormality of the power supply, the power unit, or the superconducting magnet is erroneously detected, a contact that short-circuits both ends of an output of the power unit is closed to set a protection state; and a first current detector , is arranged in the loop that has described superconducting coil and described contact, is used for detecting the electric current value in this loop, wherein, described power unit has: amplifier; The 2nd electric current detector, detects described power unit The output current value; and the current control device, which controls the output current value, the excitation power supply for the superconducting magnet also includes a reset device, after the contact is closed by the protection device, the reset device utilizes the The detected values of the first current detector and the second current detector are increased according to a predetermined scanning rate to the output current value, so that the output current value is consistent with the current value passing through the superconducting coil, and then The contact is opened to reset from the protection state.

According to the above configuration, the contact is opened after the output current value of the power unit is matched with the current value passing through the superconducting coil using the detection values of the first current detector and the second current detector, thereby preventing the contact from being damaged. The current changes abruptly after disconnection. Therefore, quenching of the superconducting coil can be prevented. That is, according to the present invention, even if the output terminals of the excitation power source are short-circuited due to erroneous detection of an abnormal state, the contacts can be disconnected by matching the output current value of the power unit with the current value passing through the superconducting coil. Quickly return to normal state (non-short circuit state).

In addition, according to the present invention, it is possible to quickly return to the normal state (non-short-circuit state). Therefore, even if the frequency of malfunctions is increased and malfunctions occur due to an increase in the detection level of abnormal states such as quenching, it is necessary to return to the normal state. The normal state doesn't take much time either. That is, even if the detection level of abnormal states such as quenching is increased, it will not cause obstacles (it does not take too much time to return to the normal state), and the contacts can be operated more sensitively by increasing the detection level of abnormal states , therefore, it is better able to prevent damage to the excitation power supply or the superconducting magnet than in the prior art.

In addition, for example, when the main power supply fails or an abnormality occurs when the internal fuse of the excitation power supply is replaced, it is necessary to deal with the abnormal situation, and when the normal state is restored by taking measures such as restoring the power supply or replacing the fuse, it can be quickly restored to the current state. Normal state (non-short circuit state).

In addition, in the description of "making the output current value of the power unit consistent with the current value passing through the superconducting coil, and then disconnecting the contacts", the so-called "consistent" does not mean completely consistent, but roughly consistent. That is, there may be a slight difference between the output current value of the power unit and the current value passing in the superconducting coil. As long as the output current value of the power unit is consistent with the current value passing through the superconducting coil, it can prevent the sudden change of the current value passing through the superconducting coil after the contact is opened and prevent the superconducting coil from quenching. That's it. In addition, the main power supply refers to a power supply that supplies electric power (feeds) to the power supply constituting the field power supply, and is a power supply on the upstream side of the field power supply.

In addition, in the present invention, the reset device may be configured to: when the reset button is pressed, read the detection value of the first current detector as the target value, and use the detection value of the second current detector The value is used as the current value, and the two detected values are consistent according to a predetermined scan rate, and then the contact is opened.

According to the above configuration, the two detection values are made to match at a predetermined scan rate, whereby damage to the power unit can be suppressed when returning from the protection state to the normal state.

Furthermore, the present invention may be configured such that the first current detector is installed at a position in the circuit where the output current value can be detected, and the current control device utilizes detection by the first current detector in a normal state. The value controls the output current value, and when the protection state is restored, the detection value of the second current detector is used to control the output current value, thereby controlling the output current for the normal state and the restoration The current detector is switched.

Compared with the output current control in the normal state, the output current control when returning from the protection state can adopt relatively lower precision. That is, according to the above configuration, a relatively low-precision current detector can be used as the second current detector, and the component cost of the excitation power supply can be reduced.

Furthermore, the present invention may be configured such that the excitation power supply has a plurality of the power units, and includes a main control device for outputting a current command value so that the detection value of the first current detector is equal to the value of the entire excitation power supply. setting the output current values to be equal; and command value distribution means for distributing the current command value output by the main control device to each power unit, wherein the first current detector detects the output of the entire excitation power supply A current detector for the current value, the second current detector is installed in each power unit, and is a current detector for detecting the output current value of each power unit, and the current control device installed in each power unit controls each power The output current value of the unit is controlled so that the detection value of the second current detector is equal to the current command value distributed by the command value distribution device.

According to the above configuration, even if a component defect occurs in an amplifier in a certain power unit among the plurality of power units and the power unit cannot discharge a stable current, the main control device can issue a current command value to compensate for it. And, the current command value is distributed to each power unit by the command value distribution device. Moreover, the current control device of each power unit controls each output current value to be equal to the current command value distributed by the command value distribution device, so the current will not be extremely biased to the normal power unit, so that the overall to prevent bias currents from occurring.

In addition, the present invention may be configured such that the first current detector is provided in series with the contact, and the output circuit of the power unit provided in the closed state of the contact is connected to the The common part of the superconducting coil side loop, the reset device sets the detection value of the first current detector as the current value when the reset button is pressed, and sets the target value of the first current detector as the current value. is 0, the power unit is controlled according to a predetermined scan rate, so that the detection value of the first current detector is consistent with 0, and then the contact is disconnected.

According to the above configuration, the detection value of the first current detector is made to match 0 at a predetermined scan rate, whereby damage to the power unit can be suppressed when returning from the protection state to the normal state.

In addition, in the above-mentioned description "make the detection value of the first current detector coincide with 0, and then open the contact", "coincidence" does not mean exactly coincidence with 0, but almost reaches 0. That is, it may not completely reach 0. The detection value of the first current detector may be matched with 0 to such an extent that a sudden change in the value of the current passing through the superconducting coil can be prevented after the contact is opened, and quenching of the superconducting coil can be prevented.

In addition, the present invention may be configured such that the first current detector is provided in series with the contact, and the output circuit of the power unit provided in the closed state of the contact is connected to the A common part of the superconducting coil side circuit, the reset device sets the added value of the detection value of the first current detector and the detection value of the second current detector as a target value when the reset button is pressed , controlling the power unit according to a predetermined scan rate, so that the detection value of the second current detector is consistent with the target value, and then disconnecting the contact. Here, it is preferable to sequentially repeat adding the detection value of the first current detector and the detection value of the second detector to sequentially update the target value.

According to the above-mentioned configuration, the control of the power unit is the same as the normal scan control, so the control is easy. In addition, the "consistent" mentioned here does not only mean completely consistent, but also includes roughly consistent meanings.

In addition, according to the second aspect of the present invention, an operation method of an excitation power supply is provided, wherein the excitation power supply excites a superconducting magnet, and the excitation power supply includes: a power supply; a power unit connected to the power supply; a protection a device, when detecting an abnormality in the power supply, the power unit, or the superconducting magnet, closes a contact that short-circuits both ends of the output of the power unit to enter a protection state; and a first current detector is provided In the loop with the superconducting coil of the superconducting magnet and the contact, it is used to detect the current value in the loop, the power unit includes: an amplifier; the second current detector detects the current value of the power unit an output current value; and a current control device for controlling the output current value, and the operation method is characterized in that after the contact is closed by the protection device, the first current detector and the second current detector are used to The detection value of the current detector makes the output current value consistent with the current value passing through the superconducting coil, and then the contact is opened, thereby returning from the protection state.

In addition, according to a third aspect of the present invention, there is provided an excitation power supply for a superconducting magnet for exciting a superconducting magnet equipped with a superconducting coil, which is characterized in that it includes: a power supply; a power unit connected to the power supply a protection device that closes a contact that short-circuits both ends of the output of the power unit to enter a protection state when detecting an abnormality in the power supply, the power unit, or the superconducting magnet; and the storage device in the After the contact is closed by the protection device, the output current value of the power unit at or before the closing time is stored, and the power unit has: an amplifier; a current detector for detecting the output current value of the power unit output current value; and a current control device, controlling the output current value, the excitation power supply for the superconducting magnet also includes a reset device, after the contact is closed by the protection device, the reset device utilizes the The detection value of the current detector and the stored value of the storage device make the output current value consistent with the current value passing through the superconducting coil, and then the contact is disconnected to return from the protection state.

According to the above configuration, one current detector can be used. Originally, assuming control by a microcomputer, almost all calculation and storage can be handled by the program (software) of the microcomputer, so there is an advantage that a current detector as a hardware component can be omitted.

In addition, the present invention may be configured to further include: a timer for measuring the elapsed time from the time when the storage means stores the output current value; and a correction means for measuring the elapsed time measured by the timer and the previously stored The correction value per unit time corrects the stored value of the storage device, wherein the reset device uses the detection value of the current detector and is corrected by the correction device after the contact is closed by the protection device After the storage value of the storage device is adjusted, the output current value is consistent with the current value passing through the superconducting coil, and then the contact is opened.

According to the above configuration, since not only the storage device but also the timer and correction device are included, it is possible to return from the protected state more reliably.

Furthermore, in the present invention described above, it is more preferable that the contact for short-circuiting both ends of the output of the power unit is the B contact. According to the above structure, even in a long-term power failure state, the non-quenched superconducting coil can be restored from the protection state to the normal state without quenching.

According to the present invention, after the above-mentioned contacts are closed by the protection device, the output current value of the power unit is consistent with the current value passing through the superconducting coil, and then the contacts are opened, thereby returning to the protection state. Thus, even if a short circuit occurs at both ends of the output of the field power supply due to false detection of an abnormal state or increased detection sensitivity of the main power supply voltage dip, the normal state (non-short-circuit state) can be quickly restored thereafter. And, for example, when the main power supply fails or an abnormality occurs during the replacement of the internal fuse of the excitation power supply, and it is necessary to deal with the abnormal situation, and return to the normal state by taking measures such as restoring the power supply or replacing the fuse, it can quickly return to the state. Normal state (non-short circuit state).

Description of drawings

FIG. 1 is a configuration diagram showing a field power supply according to a first embodiment of the present invention.

Fig. 2 is a flowchart showing the operation when returning from the protected state.

Fig. 3 is a configuration diagram showing a field power supply according to a second embodiment of the present invention.

Fig. 4 is a configuration diagram showing a field power supply according to a third embodiment of the present invention.

Fig. 5 is a configuration diagram showing a field power supply according to a fourth embodiment of the present invention.

Fig. 6 is a configuration diagram showing a field power supply according to a fifth embodiment of the present invention.

Fig. 7 is a configuration diagram showing a field power supply according to a sixth embodiment of the present invention.

Label description

1: Power

2: Superconducting magnet

2L: superconducting coil

3: Power unit

4: Protection relay

4a: Contact

5: 1st shunt resistor (1st current detector)

7: Transistor (amplifier)

8: The second shunt resistor (the second current detector)

9: Current control circuit (current control device)

16: Protection circuit (protection device)

100: Internal abnormal signal

101: Excitation power supply

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(first embodiment)

FIG. 1 is a configuration diagram showing a field power supply 101 according to a first embodiment of the present invention.

(Structure of the excitation power supply 101)

The excitation power source 101 is connected to the superconducting coil 2L, and is a power source for exciting the superconducting magnet 2 including the superconducting coil 2L. The superconducting coil 2L is wound from a superconducting wire.

As shown in FIG. 1 , the excitation power supply 101 includes a power supply 1 , a power unit 3 , a first shunt resistor (first current detector), and a protection circuit 16 (protection device).

(power supply)

The power source 1 includes a transformer (not shown) connected to an AC power source, a transistor circuit (not shown) for supplying a smooth DC current rectified by the AC power of the transformer to the superconducting coil 2L, and the like. In addition, a commercially available switching regulator or the like may be used for the power supply 1 .

(1st current detector)

As the current detector (the first current detector), a non-contact current detector that detects the magnetic field generated by the current through the Hall element can be used instead of the shunt resistor (the same is true for the second shunt resistor 8 described later). ). The first shunt resistor 5 is installed at a position where the current value in the circuit A can be detected (and is a position in the circuit A where the output current value of the power unit 3 can be detected when the contact 4a is opened), wherein, The above-mentioned circuit A includes a superconducting coil 2L and a contact 4 a of a protective relay 4 .

(power unit)

A power unit 3 is connected to the power supply 1 . The power unit 3 includes: a transistor 7 (usually a plurality of transistors) as an amplifier, and a second shunt resistor 8 (second shunt resistor 8) capable of detecting the output current value of the power unit 3 even in the protection state (the state where the contact 4a is closed). 2 current detector), a current control circuit 9 (current control device) for controlling the output current value of the power unit 3, a current command circuit 10 (current command device) for commanding a current value to the current control circuit 9, and a current command circuit 10 for instructing The scan rate setter 33 of the scan rate, the reset circuit 31 (reset device) that cooperates with the current command circuit 10 to reset from the protection state, and the reset button 32 for instructing the reset circuit 31 to reset (start reset control). In addition, it is not necessary to regard the scan rate setter 33 , the reset circuit 31 and the reset button 32 as components of the power unit 3 , that is, they can also be regarded as components different from the power unit 3 .

(amplifier)

Transistor 7 is an ordinary bipolar transistor, or various power elements such as field effect transistor (FET), IGBT, MOSFET, etc. may be used. The same applies to the transistor 17 described later.

(resetting device for resetting from protected state)

The reset circuit 31 is constituted as follows: in cooperation with the current control circuit 9, after the contact 4a is closed by the protection circuit 16 (during reset control), the detected values of the first shunt resistor 5 and the second shunt resistor 8 are used to make the power The output current value of the unit 3 matches the current value passing through the superconducting coil 2L, and then the contact 4a is opened to return from the protection state (the state where both ends of the output of the power unit 3 are short-circuited) (change to a non-short-circuit state). That is, after the contact 4a is closed by the protection circuit 16, the reset button 32 is pressed, and when the output current value of the power unit 3 is consistent with the current value passing through the superconducting coil 2L, the reset circuit 31 sends a signal to the protection relay 4 to The contact 4a is opened.

In addition, in the above-mentioned description of "making the output current value of the power unit 3 consistent with the current value passing through the superconducting coil, and then disconnecting the contact 4a", "consistent" does not only mean completely consistent, but roughly consistent . That is, there may be a slight difference between the output current value of the power unit 3 and the current value passing in the superconducting coil 2L. As long as the output current value of the power unit 3 is consistent with the current value passing through the superconducting coil 2L, it is possible to prevent the sudden change in the current value passing through the superconducting coil 2L after the contact 4a is disconnected and to prevent the superconducting coil 2L from It is only necessary for quenching to occur.

In addition, as in the present embodiment, not only the current control circuit 9 and the reset circuit 31 may be configured separately, but both may be formed as a single circuit configuration.

Moreover, in this embodiment, the current control device, reset device, and protection device are in the form of a circuit structure, but they may also be controlled by a controller controlled by a program such as a microcomputer (microcomputer). In this case, since the program setting has a degree of freedom, it is easy to change the setting. The same applies to the current command circuit 10, the current control circuit (19, 29), the distributor 14, the main control circuit 12, etc. which will be described later.

In addition, the reset circuit 31 may not be built into the exciting power supply 101, but only the first shunt resistor 5 may be used as a current display detector, and the operator (human) may manually control the reset circuit 31. See below for details.

(current command device)

The current command circuit 10 is configured to command the current value (i.e., the output current command value) to the current control circuit 9 in a normal state, for example, when the current is increased by an operation switch not shown for excitation, so that the current value is set according to the scan rate The amount of increase determined by the setter 33 gradually increases the command current. The current control circuit 9 is configured to control the output current value of the power unit 3 based on the current command value output from the current command circuit 10 and the detection value of the second shunt resistor 8 . Here, the normal state refers to a state in which the contacts 4a are open (non-short-circuited state).

Furthermore, when returning from the protected state, the reset circuit 31 uses the detection value (current detection value) of the first shunt resistor 5 as a target value, and cooperates with the current command circuit 10 to output a current value to the current control circuit 9 . And reset circuit 31 cooperates with current control circuit 9, reads in the detection value of the first shunt resistance 5 as target value, after making this target value coincide with the detection value of the 2nd shunt resistance 8, disconnect contact 4a ( The output current value of the power unit 3 is controlled using the detected value of the second shunt resistor 8. The detected value of the first shunt resistor 5 is used as a target value). Here, the protected state refers to a state in which the contacts 4a are closed (short-circuited state). Return refers to the process from the closed state to the open state.

In addition, in general, when current feedback control is performed using a current shunt, the commanded current is feedback-controlled, so basically, when the command is issued, the output current will be adjusted in real time to the above-mentioned commanded current. In the above description, for ease of understanding, it has been described so as to match the detected value of the second shunt resistor 8 . In fact, the specific method adopted is: if the output value of the current command circuit 10 is consistent with the value of the first shunt resistance 5 as the target value, the current control circuit 9 compares the second shunt resistance 8 with the above-mentioned command value And adjust immediately, so "the detection value of the second shunt resistance 8" can be regarded as "the output command value of the current command circuit 10". In addition, as described at the beginning, it is also possible to actually use the detection value of the second shunt resistor 8 to check whether or not they match.

In addition, an internal abnormality signal 100 , which is generated by a controller (not shown) using the microcomputer or the like, indicating a voltage dip abnormality, a power failure, etc., is also input to the protection circuit 16 (protection device).

(protective relay)

The protective relay 4 has a contact 4a. The contact 4 a is provided at a position to short-circuit both ends of the output of the power unit 3 . In other words, the contact 4a is provided at a position that short-circuits both ends of the superconducting coil 2L. The contact 4a of the protective relay 4 may be composed of an A contact or a B contact. When the contact 4 a of the protective relay 4 is constituted by an A contact, the contact 4 a is closed when the electrical signal is ON, and is opened when the electrical signal is OFF. When the contact 4a of the protective relay 4 is constituted by a B contact, the contact 4a is closed when the electric signal is OFF, and the contact 4a is open when the electric signal is ON. That is, the B contact is an electrical contact characterized by being in a closed state by the restoring force of the spring when the relay (protective relay 4) is not powered, and being closed by the electromagnetic force when the relay (protective relay 4) is powered. force and is in a disconnected state.

In addition, in consideration of a power failure state (a state in which the relay (protective relay 4) is not powered), it is preferable that the contact 4a of the protective relay 4 is constituted by a B contact (normally closed). The same applies to the embodiments described later. If the contact 4a is composed of B contacts, then, in the power failure state, even if the reset circuit 31 (reset device) does not act due to a power failure, the two ends of the output can still be short-circuited due to the closure of the contact 4a. Therefore, the current flowing through the unquenched superconducting coil 2L can flow back through the contact 4a. Afterwards, when the main power supply is restored, the protected state can be restored to the normal state through the action of the reset circuit 31 (reset device). On the other hand, in the case where the contact 4a is composed of an A contact, if the power failure time is relatively short, the reset circuit 31 will still operate; open. As a result, the current flowing through the unquenched superconducting coil 2L cannot be recirculated.

Here, the protection circuit 16 is an overvoltage detection circuit. The protection circuit 16 is configured such that, for example, when the set value of the excitation voltage of the superconducting coil 2L is 10V, if the excitation voltage exceeds 12V, it is judged as an overvoltage (abnormal) and sends a signal to the protection relay 4 and the current command circuit 10 . In addition, there are various protection circuits and are not limited to overvoltage detection circuits.

Here, the current command circuit 10 is configured to issue a command to the current control circuit 9 so that the output current of the power unit 3 is zero when receiving a signal from the protection circuit 16 . Furthermore, protective relay 4 is configured to close contact 4 a when receiving a signal from protective circuit 16 .

In this embodiment, the case where the protection circuit 16 is incorporated into the excitation power supply 101 to detect whether or not there is an abnormality in the superconducting magnet 2 is exemplified. This embodiment can also be configured as follows: a circuit (device) that detects whether there is an abnormality in the power supply 1 and the power unit 3 is incorporated in the excitation power supply 101, and the quench detection information is added to the circuit, and the circuit is sent to the protective relay 4 and The current command circuit 10 sends out a signal. The circuit for detecting whether there is an abnormality in the power supply 1 and the power unit 3 is, for example, a circuit for detecting abnormalities such as overheating, overcurrent, main power supply voltage dip, and power failure of the power supply 1 and power unit 3 .

(protection state reset control of excitation power supply)

Next, the restoration control of the protected state will be described. Fig. 2 is a flowchart showing the operation when returning from the protected state.

When the protection circuit 16 detects that the superconducting magnet 2 is abnormal, the contact 4 a is closed by the protection relay 4 through the protection circuit 16 , and the output current of the power unit 3 is 0 through the current control circuit 9 . At this time, as shown by IA in FIG. 1 , the current passing through the superconducting coil 2L passes through the circuit A including the superconducting coil 2L and the contact 4 a of the protective relay 4 . On the other hand, the current IB passing from the transistor 7 of the power unit 3 becomes zero. The same applies when abnormalities of the power supply 1 and the power unit 3 are detected.

Here, when a quench occurs in the superconducting coil 2L, since the superconducting coil 2L is in a normally conductive state and there is resistance, IA rapidly decays. However, factors such as noise may cause the protection circuit 16 to malfunction. In addition, there are cases where a transient voltage occurs in the superconducting coil 2L but then returns to the superconducting state. In addition, an insignificant voltage drop of the main power supply may also cause the protection circuit 16 to operate. In the above case, since the superconducting coil 2L is in a superconducting state, the resistance of the loop A is extremely small, and it may take about one day for the current IA to become zero. Although the current IA can be made 0 by opening the contact 4a, this operation will cause the superconducting coil 2L to be quenched. The damage that the forced quench will bring to the superconducting coil 2L.

Here, in the field power supply 101, control is performed as in the flow shown in FIG. 2 . When the reset button 32 is pressed (S1, short for step 1), the current command circuit 10 outputs the current value to the current control circuit 9 with the detection value (current value) of the first shunt resistor 5 as a target value. The current control circuit 9 reads the detected value (current value) of the first shunt resistor 5 as a target value (S2). Then, the current control circuit 9 sets the read target value of the first shunt resistance 5 as a set value ( S3 ). In addition, the current control circuit 9 reads the value of the scan rate set in advance or the value of the scan rate from the scan rate setter 33 through the current command circuit 10 ( S4 ). Then, the current command circuit 10 increases the current command value output to the current control circuit 9 according to a predetermined scan rate, so that the detected value of the second shunt resistor 8 (the output current value of the power unit 3) is consistent with the set value (S5) . Repeat S2-S5 until IA and IB are consistent. Then, when it is confirmed that IA=IB, the reset circuit 31 sends a signal to the protective relay 4 to open its contact 4a, and the contact 4a is opened (S6). In addition, regarding IA=IB, IB may actually be the detected value of the second shunt resistor 8 , or may be a current command value output from the current command circuit 10 to the current control circuit 9 . In addition, in the above process, the value of the first shunt resistance 5 is read in every time in S2, but because the processing time is short, the attenuated coil current (IA) during it is extremely small, therefore, it can also be used to execute only once After S2, the methods of S3-S6 are repeatedly executed.

(second embodiment)

FIG. 3 is a configuration diagram showing a field power supply 201 according to a second embodiment of the present invention. The only difference from the first embodiment lies in the position of the first shunt resistor (first current detector). In the present embodiment, the first shunt resistor 5 is provided in parallel with the superconducting coil 2L. In this way, the first shunt resistor 5 may be provided at a position where the current IA passing through the superconducting coil 2L after the contact 4a of the protective relay is closed can be detected. In other words, the first shunt resistor 5 is arranged in series with the contact 4a, and is arranged between the output circuit B of the power unit 3 and the circuit A on the side of the superconducting coil 2L when the contact 4a is closed. public part.

In this embodiment, the current control circuit 9 increases the output current value of the power unit 3 at a predetermined scan rate, so that the detection value (current detection value) of the first shunt resistor 5 becomes zero. The detection value of the first shunt resistor 5 being 0 means that IA and IB flowing in opposite directions agree with each other. When it is confirmed that IA=IB, the current control circuit 9 sends a signal to the protective relay 4 to disconnect the contact 4a, and the contact 4a is disconnected.

In addition, as a modified example, it may be configured such that when the reset button 32 is pressed, the added value of the detected value of the first shunt resistor 5 and the detected value of the second shunt resistor 8 is set as a target value, and the predetermined The scanning rate makes the detection value of the second shunt resistor 8 coincide with the target value, and then the contact 4a is opened. Here, it is preferable to sequentially repeat the addition calculation of the detection value of the first shunt resistance 5 and the detection value of the second shunt resistance 8, and update the target value sequentially. IA flows in the opposite direction to IB and is a larger current than IB, so the detection value of the first shunt resistor 5 is "IA-IB". The detected value of the second shunt resistor 8 is "IB". Therefore, the added value of the detection value of the 1st shunt resistance 5 and the detection value of the 2nd shunt resistance 8 is "IA".

As another modified example, the following control is performed in combination with the above-mentioned control method, that is, when the reset button 32 is pressed, it is controlled according to a predetermined scan rate so that the detection value of the first shunt resistor 5 is consistent with 0, and according to The predetermined scan rate is controlled so that the detected value of the second shunt resistor 8 coincides with the added value of the detected value of the first shunt resistor 5 and the detected value of the second shunt resistor 8 . Then, control is performed so that the contact 4a is disconnected at the earlier stage of the following two stages, that is: at the stage where the detected value of the first shunt resistor 5 coincides with 0; A stage in which the detected value of the first shunt resistor 5 and the added value of the detected value of the second shunt resistor 8 coincide. By configuring the excitation power supply as described above, it is possible to return to the normal state (non-short-circuit state) more quickly.

As mentioned above, according to the present invention, the output current value of the power unit 3 is made consistent with the current value passing through the superconducting coil 2L by using the detection values of the first shunt resistance 5 and the second shunt resistance 8, and then the contactor is opened. Point 4a, thereby preventing sudden changes in current after the contacts are opened. Therefore, quenching of the superconducting coil 2L can be prevented. That is, according to the present invention, even if the output terminals of the excitation power supply (power unit 3) are short-circuited due to erroneous detection of an abnormal state, the output current value of the power unit 3 and the current value passing through the superconducting coil 2L can be adjusted After matching, the contact 4a is opened to quickly return to the normal state (non-short-circuit state).

In addition, according to the present invention, it is possible to quickly return to the normal state. Therefore, for example, even if the occurrence frequency of malfunctions increases due to an increase in the abnormal state detection level of the protection circuit 16 and malfunctions occur, it is not necessary to return to the normal state. It takes too much time. That is, even if the detection level of the abnormal state such as quenching is increased, there is no obstacle (it does not take too much time to return to the normal state), and the contact 4a can be more sensitively carried out by increasing the detection level of the abnormal state. Action, therefore, can prevent damage to the field power supply (101, 201) or the superconducting magnet 2 better than the prior art. The same applies to abnormalities that occur inside the excitation power supply, main power supply voltage dips, and power failures.

In addition, in the first embodiment, the first shunt resistance 5 that detects the current passing through the superconducting coil 2L in the loop A is used, and the detected value is used as the target value. As a modified example, it can be configured as follows: In the normal state, the output current value of the power unit 3 is controlled by the detection value of the first shunt resistance 5, and the output current value of the power unit 3 is controlled by the detection value of the second shunt resistance 8 when returning from the protection state . As mentioned above, the control in the excitation power supply 101 is specifically: switching the current detector used for output current control in the normal state and in the reset state. On the other hand, compared with the output current control in the normal state, the output current control when returning from the protection state can adopt relatively lower precision. That is, the advantage of the above structure: the second shunt resistor 8 adopts a relatively low-precision current detector, even under the protection state (the state of the contact 4a closed), the first shunt resistor 5 with higher precision can The current passing through the superconducting coil 2L is detected (displayed) with higher accuracy.

In addition, in the first embodiment, the second shunt resistor 8 is used to control the output current value of the power unit 3 at the time of normal state and reset, and the first shunt resistor 5 can be used only for display. In this case, when resetting from the protection state, the operator can set the display value of the first shunt resistor 5 as the set value for resetting and increase the output current value of the power unit 3. When IA and IB are consistent Opening contact 4a completes the reset. Furthermore, in the above description, it is finally up to the operator to check whether or not IA and IB match. Then, the operator presses a button that manually opens the contact 4a.

(third embodiment)

FIG. 4 is a configuration diagram showing a field power supply 301 according to a third embodiment of the present invention. This embodiment differs from the first embodiment mainly in that the field power supply 301 of this embodiment includes two (multiple) power units. In addition, the field power supply may include three or more power units.

As shown in Figure 4, the excitation power supply 301 includes a power supply 1, a first power unit 13, a second power unit 23, a first shunt resistor 5 (first current detector), a main control circuit 12 (main control device), a distribution Device 14 (command distribution device), scan rate setter 33, protection circuit 16 (protection device), reset button 32 and reset circuit 131.

(1st current detector)

The first shunt resistor 5 is a current detector that detects the output current value of the entire excitation power supply 301 . In addition, the first current detector is installed to be able to detect the output current value in the circuit A including the superconducting coil 2L and the contact 4a of the protective relay 4 (the overall output current value of the two power units 12 and 13) in the protected state. )s position.

(power unit)

Two power units 13 and 23 are connected to the power supply 1 . The first power unit 13 is provided with a transistor 17 (usually a plurality of transistors) as an amplifier, a second shunt resistor 18 (second current detector) for detecting the output current value of the power unit 13, and controlling the output current value of the power unit 13. The current control circuit 19 (current control device).

The structure of the second power unit 23 is the same as that of the first power unit 13, and the second power unit 23 has a transistor 27 (usually a plurality of transistors) as an amplifier, and a second shunt resistor 28 for detecting the output current value of the power unit 23 ( second current detector) and a current control circuit 29 (current control device) that controls the output current value of the power unit 23 .

In addition, the main control circuit 12, distributor 14, switch 30, reset circuit 131, reset button 32 and scan rate setter 33 can also be regarded as components of the power units 13 and 23 (the common components of the power units 13 and 23 part).

(master control unit)

The main control device 12 is used to set and control the output current value of the excitation power supply 301 as a whole, and the setting function part of the main control circuit 12 includes a digital-to-analog conversion circuit (DAC). By setting the output current value to be held by the excitation power supply 301 , the output current value simulated from the microcomputer circuit through the DAC is output to the control part in the main control circuit 12 as a command value.

The control section of the main control circuit 12 is configured to output a current command value to the distributor 14 so that the detected value (current value) of the first shunt resistor 5 is equal to the set output current value of the excitation power supply 301 as a whole. Specifically, it is configured to obtain a deviation between the detected value of the first shunt resistance 5 and the set output current value, and output a current command value proportional to the obtained deviation to the distributor 14 .

(command distribution device)

The distributor 14 is configured to distribute the current command value output from the main control circuit 12 to each power unit (13, 23). In addition, when the current capacities of the first power unit 13 and the second power unit 23 are equal, the distributor 14 equally distributes the current command value output from the main control circuit 12 . When the current capacity ratio of the first power unit 13 and the second power unit 23 is 2:3, the distributor 14 distributes the current command value output from the main control circuit 12 at a ratio of 2:3.

(Regarding current control circuits 19 and 29)

Here, the current control circuits 19 and 29 provided in the respective power units 13 and 23 are configured to control the output current values of the respective power units 13 and 23 so that the detection values (current values) of the second shunt resistors 18 and 28 correspond to The current command values distributed and output by the distributor 14 are equal.

The protection relay 4 is configured to close the contact 4 a when receiving a signal from the protection circuit 16 . In addition, an internal abnormality signal 100 , which is generated by a controller using a microcomputer (not shown) or the like, indicating an abnormality such as a voltage dip abnormality or a power failure, is also input to the protection circuit 16 (protection device). Furthermore, when receiving a signal from the reset circuit 131 (state of IA=IB1+IB2), the protective relay 4 opens the contact 4a.

(switch)

The switch 30 is used to switch the signal from the main control circuit 12 and the signal from the reset circuit 131 and input one of them into the distributor 14 . Switch 30 is activated by reset circuit 131 .

(Operation of excitation power supply)

Next, the operation of the excitation power supply 301 in the normal state (unprotected state) will be described.

In the normal state of non-protection circuit activation (contact 4a closed state) or non-reset mode (starting from the contact 4a closed state, making IA and IB consistent, and then opening the series state of the contact 4a), this embodiment The excitation power supply 301 has the function of preventing or alleviating the current bias phenomenon. The bias current phenomenon here refers to: when a problem such as defective components or conductor deterioration occurs inside a certain power unit for some reason, the output current of the power unit that has the problem is compensated by other normal power units, resulting in current Bias current to other normal power units above.

As a case where the current bias phenomenon occurs, for example, the temperature inside the first power unit 13 rises due to the decrease in the performance of the cooling device (not shown) provided in the first power unit 13. Therefore, compared with other normal second power In the unit 23 , a large amount of current flows through the first power unit 13 . In this case, in order to compensate for the excessive current flowing through the first power unit 13, the current passing through the second power unit 23 is less than that of the first power unit 13 (bias current phenomenon). In addition, for example, the bias current phenomenon may also be caused by deterioration of elements such as the transistor 17 in the first power unit 13 .

According to the excitation power supply 301 of this embodiment, the main control circuit 12 controls to output the current command value to the first power unit 13 and the second power unit 23 so that the voltage obtained by measuring the voltage generated at both ends of the first shunt resistor 5 is When the output current value reaches the output current value set in the overall current setting command unit (not shown), the distributor 14 distributes the current command value output by the main control circuit 12 to the first power unit 13 and the second power unit 23 . And, the current control circuit 19 (current control circuit 29) of the first power unit 13 (the second power unit 23) controls so that by measuring the current generated at both ends of the second shunt resistance 18 (the second shunt resistance 28), The output current value detected by the voltage reaches the current command value distributed by the distributor 14 . As a result, when components such as the transistor 17 in the first power unit 13 are defective and the first power unit 13 cannot output a given current, the main control circuit 12 issues a current command value to compensate for it, and The current command value is distributed to the first power unit 13 and the second power unit 23 by the distributor 14 . Moreover, the current control circuit 19 of the first power unit 13 and the current control circuit 29 of the second power unit 23 control so as to reach the current command value distributed by the distributor 14, so that the normal second power unit 23 will not be generated. Extreme current bias, so that the current is averaged across the board to prevent current bias.

In addition, compared with the amplification ratio of the main control circuit 12 , the amplification ratios of the current control current 19 and the current control circuit 29 are smaller. Therefore, the current control circuit 19 of the first power unit 13 and the current control circuit 29 of the second power unit 23 allow a slight bias current phenomenon, and the main control circuit 12 performs strict current control, and the overall passing current is expected to be stable. change. That is, it is possible to prevent an extreme current bias phenomenon from occurring in the field power supply 301 as a whole.

In addition, compared with the second shunt resistors 18 and 28, the first shunt resistor 5 uses a high-precision resistor. Thereby, the cost of the field power supply 301 can be reduced.

In addition, the dispenser 14 does not necessarily have to adopt the structure of this embodiment. It is only necessary that the overall control system (the current command value of the entire field power supply 301 (the entire power unit)) be divided into the current commands of the power units 13 and 23 and input.

(Description of protection status)

In addition, when the protection circuit 16 detects a quench during the energization process of the superconducting coil 2L, its signal enters the main control circuit 12 through the protection circuit 16 and sets the current command to zero. Thus, IB1 and IB2 output from the power elements 17 and 27 become 0. At the same time, the protection circuit 16 closes the contact 4a. The current IA previously passed through the superconducting coil 2L passes through the contact 4a. Here, when the superconducting coil 2L is truly quenched, IA rapidly decays. On the other hand, when a miss is detected by mistake, the IA hardly decays, so the decay takes a long time.

Therefore, when the reset button 32 is pressed, the reset circuit 131 first switches the output of the main control circuit 12 to the output of the reset circuit 131 . The contact that switches switch 30 from 30a to 30b. Similar to the main control circuit 12 , the detected value of the current is input to the reset circuit 131 through the first shunt resistor 5 . The reset circuit 131 uses the detection value of the first shunt resistance 5 as a target value, generates a command value for gradually increasing the current command based on the value of the scan rate setter 33 , and outputs it to the distributor 14 . As in the normal state (non-protection state), the distributor 14 distributes current commands to the two power cells ( 13 and 23 ). When the command current reaches the target value IA at the scan rate determined by the reset circuit 131 , the total value of the currents IB1 and IB2 of the two allocated power units ( 13 and 23 ) agrees with IA.

As described above, the excitation power supply 301 has the same function as the excitation power supply in the first and second embodiments, that is, the reset circuit 131 is activated, and the detected values ( The total value of the detection values of the second shunt resistors 18 and 28) makes the output current value of the power unit as a whole coincide with the current value passing through the superconducting coil 2L, and then opens the contact 4a, thereby preventing the contact from being disconnected. After 4a, the current changes abruptly.

In addition, the difference between the reset mode and the normal mode is: in the normal mode, the overall current is measured by the first shunt resistor 5, and is output to the distributor 14 to correct the error between the overall command; in the reset mode In this case, only the current command value generated by the reset circuit 131 is output to the distributor 14 . As a result, IB1 and IB2 are controlled with the precision of the second shunt resistors 18 and 28 . Here, for example, from the viewpoint of cost reduction, the second shunt resistors 18 and 28 use current detectors (current detectors with lower accuracy of current detection) than the overall shunt (first shunt resistor 5 ) with lower accuracy. . In addition, each unit (power units 13 and 23) uses a lower feedback gain due to the dual control system. Therefore, IB1 and IB2 are rough values compared with the normal mode. (IB1+IB2)≈IA is enough, as long as they are roughly consistent, they can return to the normal mode later, so some errors are allowed.

When IB1+IB2 is substantially consistent with IA, the reset circuit 131 transmits the current current value IA to the main control circuit 12 . Then, the switch 30 is switched to the 30a side while opening the contact 4a. Then, in the normal mode, current control is performed to keep the current at the set current value IA. In addition, IA can adopt the value stored by the main control circuit 12 when a quench occurs. If the detection current value IA is used, when returning to the normal mode, there will be a slight error with the current value of the superconducting coil 2L that is intended to be controlled. Therefore, at this time, fine-tuning is performed by the usual method.

In addition, in the third embodiment, the circuit configuration has been described separately from the main control circuit 12 and the reset circuit 131. In terms of functions, there is a current detection value of the first shunt resistor 5 as a feedback signal (main control circuit). The difference from using the current detection value of the first shunt resistor 5 as the target value (reset circuit), and the output value of the distributor 14 is slightly different, but in the circuit structure, the signal input of the first shunt resistor 5 is received , receiving a signal from the scan rate setter 33, and generating a current signal at a predetermined scan rate are the same. Usually, these processes are output after analog conversion by a microcomputer and a DA converter. Therefore, (1) whether there is an input of the reset button 32, (2) the difference in the processing of the detected value of the first shunt resistor 5, ( 3) The difference in the content of the signal output to the distributor is a slight difference in the program of the built-in microcomputer, so it is preferable to integrate the main control circuit 12 and the reset circuit 131 .

(fourth embodiment)

FIG. 5 is a configuration diagram showing a field power supply 401 according to a fourth embodiment of the present invention. The field power supply 401 of this embodiment is a modified example of the field power supply 301 of the third embodiment. As shown in Figure 5, the excitation power supply 401 includes a power supply 1, a first power unit 13, a second power unit 23, a first shunt resistor 5 (first current detector), a main control circuit 12 (main control device), a distribution Device 14 (command distribution device), scan rate setter 33, protection circuit 16 (protection device), reset button 32 and reset circuit 231.

Hereinafter, for example, reset control after the contact 4a is closed by the protection circuit 16 will be described. After the current value of IA is detected by the first shunt resistor 5, it is used as the target value control (IB1+IB2). The adder 304 of the total value of the detected current values obtains (IB1+IB2). From the adder, a switching signal is input to the main control circuit 12 through the switches 302 and 303 instead of the signal from the first shunt resistor 5 in the normal mode. The switches 302 and 303 operate (switch) according to a signal from the reset circuit 231 .

When IA and (IB1+IB2) coincide, switch contact 4a and switches 302 and 303 through reset circuit 231 to return to normal state (disconnect contact 4a. Switches 302 and 303 are respectively switched to 302a and 303a.). When the switches 302 and 303 are switched to 302a and 303a respectively, it is the normal mode, and when they are switched to 302b and 303b, it is the reset mode. Furthermore, the detection value of the first shunt resistor 5 may always be input to the main control circuit 12 to correspond to the gradually attenuated IA.

In the reset mode (reset control), since the sum of the current detection values of the second shunt resistors 18 and 28 for preventing bias current is used instead of the first shunt resistor 5, for cost considerations, the second shunt resistor Resistors 18 and 28 may use lower precision current detectors. In this case, the detection accuracy of the current decreases only at the time of reset (during reset mode). However, after resetting, it becomes the normal mode, and the first shunt resistor 5 (integral shunt) is used for control, so the subsequent current control accuracy returns to normal. The function of this reset mode is to prevent the large current change of the superconducting coil 2L during the reset so as not to cause quenching and other phenomena. The above-mentioned level of error (the error of the current measurement accuracy) will not produce a large current change. , so there is no problem.

(fifth embodiment)

FIG. 6 is a configuration diagram showing a field power supply 501 according to a fifth embodiment of the present invention. In the excitation power supply 501 of the present embodiment, the first shunt resistor 5 used in the excitation power supply 101 of the first embodiment is omitted, and the storage circuit 50 is built into the power unit 43 instead. The storage circuit 50 is a storage device that stores the output current value of the power unit 43 at the time when the contact 4 a is closed after the reset circuit 31 closes the contact 4 a or before the closing time. In addition, in the example shown in FIG. 6, the structure in which the detection value of the shunt resistor 8 (current detector) is stored by the storage circuit 50 is adopted, but the current command sent to the current control circuit 9 may be stored by the storage circuit 50. The structure of the value. Storage comes in a variety of forms, including non-volatile storage in addition to battery-backed RAM. In addition, it is usually stored in a storage device via an ADC (Analog-to-Digital Converter) or the like for digitization.

In addition, the reset circuit 31 of this embodiment is configured as a reset device, that is, after the contact 4a is closed by the protection circuit 16, the output of the power unit 43 is adjusted by using the detection value of the shunt resistor 8 and the stored value of the storage circuit 50. The current value matches the current value passing through the superconducting coil 2L, and then the contact 4a is opened to return from the protected state. Hereinafter, a specific description will be given.

For example, when an abnormality in the superconducting magnet 2 is detected, the protection circuit 16 sends signals to the storage circuit 50 , the current command circuit 10 , and the protection relay 4 almost simultaneously. The storage circuit 50 stores the output current value of the power unit 43 at that moment. The current command circuit 10 sets the current command value sent to the current control circuit 9 to zero, thereby making the output of the power unit 43 zero. In addition, the contact 4 a is closed by the operation of the protective relay 4 , thereby short-circuiting the output of the power unit 43 . In addition, the protection circuit 16 sends a signal to the storage circuit 50 when the storage circuit 50 can store the output current value before the contact 4a is closed and before the output of the power cell 43 drops to 0 (normal state).

In addition, of course, when the control including abnormal processing is performed by a microcomputer or a sequence controller, it is difficult to input the signal of the momentary power failure detection circuit built in these devices into the protection circuit 16 (when a momentary power failure is detected, the state is output to the outside, The sequence controller itself stops, so it cannot be used afterwards), therefore, a momentary power failure detection circuit is provided separately and the signal is input to the protection circuit 16, or, for example, if there is a microcomputer or a sequence controller not used for abnormal processing, these The signal of the momentary power failure detection circuit built in the device is input into the protection circuit 16 . Moreover, in order to make the controlled microcomputer, sequence controller or other equipment still be able to temporarily (for example, about 3 seconds) function after the momentary power failure of the main power supply is detected by the momentary power failure detection circuit, it is necessary to have a higher than usual A large electrolytic capacitor, or a device that can be switched to a battery drive, wherein the above-mentioned control includes exception handling.

Here, when an abnormality in the superconducting magnet 2 is erroneously detected, the current IA is attenuated by L and R, but since L is extremely large and R is extremely small, the attenuation is small, for example, only about 1% after 5 minutes. On the other hand, if the operator finds an abnormal state, the operator presses the reset button 32 . Thus, the reset circuit 31 reads the stored value of, for example, 200A in the storage circuit 50, and controls the output IB of the power unit 43 to 200A. When an instruction to control IB to 200A is issued, the reset circuit 31 judges that IB and IA are consistent, and the reset circuit 31 opens the contact 4a. In fact, even if IA decays to 198A, if it is such a difference, the superconducting magnet 2 will not be quenched or the excitation power supply 501 itself will fail, but the current passing through the magnet will be directly adjusted to 200A.

Depending on the excitation power supply 501, one current detector may be used. Originally, assuming that a microcomputer is used for control, almost all calculation and storage are performed by the program (software) of the microcomputer, and thus there is an advantage that a current detector as a hardware component can be omitted.

(sixth embodiment)

Fig. 7 is a configuration diagram showing a field power supply according to a sixth embodiment of the present invention. The field power supply 601 of this embodiment is a modified example of the field power supply 501 of the fifth embodiment. In this embodiment, the power unit 53 further includes a timer 51 and a correction circuit 52 .

The timer 51 is a timer for measuring the elapsed time from the time when the storage circuit 50 stores the output current value of the power unit 53 . In addition, the correction circuit 52 is a correction device of a current value for correcting the stored value of the storage circuit 50 based on the elapsed time measured by the timer 51 and the correction value per unit time stored in advance.

In addition, the reset circuit 31 of this embodiment is configured such that after the contact 4a is closed by the protection circuit 16, the reset circuit 31 uses the detected value of the shunt resistor 8 and the stored value of the storage circuit 50 corrected by the correction circuit 52 to make the power unit The output current value of 53 coincides with the current value passing through the superconducting coil 2L, and then the contact 4a is opened. Hereinafter, a specific description will be given.

For example, assuming that the protection relay 4 operates to close the contact 4a due to false detection of an abnormality in the superconducting magnet 2, the operator finds the abnormal state after 5 minutes, and the operator presses the reset button. At this time, the reset circuit 52 reads the stored value of, for example, 200A in the storage circuit 50 and also reads the value of, for example, 5 minutes (measured elapsed time) of the timer 51 . Then, the correction circuit 52 estimates (calculates) the IA that should have been attenuated from the value of 200A and 5 minutes. For a short time, the decay curve is a straight line. If the attenuation rate of attenuating 0.4A per minute and the correction value are stored in the correction circuit 52 in advance, it can be easily calculated by the correction circuit 52 that 2A should be attenuated in 5 minutes. If it is assumed that the difference between the closing time of the contact 4a and the time when the operator presses the reset button is a long time, the correction circuit 52 can be made to perform more complicated calculations. For example, L and R can be stored in advance, so that the correction circuit 52 can perform more complicated calculations, for example, obtain the attenuation of the current from the above-mentioned values of L and R and the measured elapsed time. If control is performed using a microcomputer, it is preferable that the correction circuit 52 is integrated with other circuits such as the storage circuit 50 and constituted by a microcomputer.

Then, the reset circuit 31 reads in the correction value 198A (200−0.4×5), and controls the output IB of the power unit 53 to be 198A. At the moment when an instruction to control IB to 198A is issued, the reset circuit 31 judges that IB and IA are consistent, and the reset circuit 31 opens the contact 4a.

The excitation power supply 601 further includes the timer 51 and the correction circuit 52 , and therefore can be restored from the protected state more reliably than the excitation power supply 501 . In addition, it is preferable to set a resettable time limit in the excitation power supply 501 and the excitation power supply 601 . It is preferable to set a resettable time limit so that the excitation power supply 501 can be reset within, for example, 10 minutes, and that in the excitation power supply 601, it can be reset within, for example, 3 hours, although it depends on the size of the calculation error. Also, the method of replacing the excitation power sources 501 and 601 of the memory circuit 50 and the like with the first shunt resistor 5 can be applied not only to the excitation power source 101 but also to the excitation power sources 201 , 301 and 401 .

(Processing after a voltage dip is detected)

In all the above-mentioned embodiments, the processing after the sudden voltage drop is detected is as follows. For example, when a microcomputer (not shown) detects a sudden drop in voltage, it sets the current command value to 0 and closes the contact 4a. When the contact 4a is closed, a current circulates in the superconducting magnet 2 via the contact, and the current continues to pass through the superconducting coil 2L. The resistance in the superconducting magnet 2 is 0. In addition, the resistances of the wires connecting the excitation power supply and the superconducting magnet 2, the contact resistance of the contacts, the shunt 5, etc. are extremely small, and the superconducting magnet 2 stores The energy consumption ratio is extremely small, and if it is a short time, the passing current will not decrease. For example, if the abnormal state lasts for 5 minutes, the decay rate is only about 1%.

Assume that the operator presses the reset button after confirming the abnormal state caused by the sudden drop in voltage. For example, when the device used at a current of 200A decays to IA=198A in a short-circuit state, after adjusting to IB=198A through the reset process, After the open contact 4a is switched to the current supply by the power unit, it can be restored to 200A again. Therefore, there is no actual damage to the operation using the magnetic field, and resetting can be performed. In addition, a power supply recovery confirmation function of the instantaneous power failure detection circuit may be added, and the power supply recovery confirmation signal may be used instead of pressing the reset button 32 . On the other hand, even if a UPS for power failure is installed, only the control system is backed up. In many cases, the power system cannot be backed up due to its large scale. In this case, even if the control can be performed, the power unit cannot be started. Shorting is effective.

As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, Various changes are possible within the range described in a claim.

Claims (3)

1. The excitation power supply for superconducting magnets is used to excite superconducting magnets with superconducting coils, which is characterized in that it includes: power supply; a power unit connected to the power supply; a protection device that closes a contact that short-circuits both ends of the output of the power unit and sets it as a protection state when it detects an abnormality in the power supply, the power unit or the superconducting magnet by mistake; and a first current detector, disposed in a circuit comprising the superconducting coil and the contact, for detecting a current value in the circuit, Wherein, the power unit has: amplifier; a second current detector for detecting the output current value of the power unit; and current control means to control the output current value, The excitation power supply for the superconducting magnet further includes a reset device, and after the contact is closed by the protection device, the reset device uses the detected values of the first current detector and the second current detector , increasing the output current value according to a predetermined scanning rate, so that the output current value is consistent with the current value passing through the superconducting coil, and then disconnecting the contact to restore from the protection state. 2. The excitation power supply for superconducting magnets as claimed in claim 1, wherein The reset device is configured to: when the reset button is pressed, read in the detection value of the first current detector as a target value, and use the detection value of the second current detector as a current value, according to a predetermined The scan rate brings the two sensed values into agreement, after which the contacts are opened. 3. The excitation power supply for superconducting magnets as claimed in claim 2, wherein: The first current detector is arranged at a position in the loop capable of detecting the output current value, The current control device is configured to control the output current value by using the detection value of the first current detector in a normal state, and use the detection value of the second current detector when returning from the protection state. The output current value is controlled, whereby a current detector for output current control is switched between the normal state and return from the protected state.

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