CN104835611A - Superconducting magnet system and quench protection method of high temperature superconductor lead thereof - Google Patents

Abstract

The invention relates to a quench protection method for a superconducting magnet system and a high-temperature superconducting wire, wherein the superconducting magnet system includes: a superconducting coil, a high-temperature superconducting wire, a heater, a heater trigger, and a high-temperature superconducting wire detection unit. The high-temperature superconducting wire detection unit is used to detect the working state of the high-temperature superconducting wire, and when the detection signal from the high-temperature superconducting wire is greater than a preset value, the high-temperature superconducting wire detection unit outputs a control signal to the A heater trigger is used to trigger the heater to work to quench the superconducting coil, and the preset value corresponds to the quench point or the quench critical point of the high-temperature superconducting wire.

Description

Quench protection method for superconducting magnet system and high temperature superconducting lead

technical field

The invention relates to a superconducting magnet system, in particular to a superconducting magnet system with quench protection for high-temperature superconducting leads and a quench protection method thereof.

Background technique

With the vigorous development of superconducting technology and superconducting materials, superconducting magnets have broad application prospects. Due to the advantages of small size, high current density, low energy consumption, and high magnetic field strength, superconducting magnets are increasingly used in basic scientific research, medical and health, transportation, and national defense industries. For example, in Magnetic Resonance Imaging (MRI) systems, superconducting magnets are used to generate a uniform magnetic field.

Superconducting magnets are usually operated at a higher current (for example, about 200A-800A) to provide energy to obtain a uniform magnetic field. The high current is usually supplied by an external power source and transmitted to the superconducting coils of the superconducting magnet through a pair of current leads. For superconducting magnets, some conduction cooling devices are arranged therein for cooling operation of the coil during charging and discharging of the coil. However, the existing conduction cooling device usually does not have redundant cooling energy to cool the current leads during the process of charging and discharging the coil. Currently, some current leads employ high-temperature superconducting (HTS) leads as part of the pair of current leads to reduce the thermal load on the superconducting magnet system.

As an example, FIG. 1 shows a schematic diagram of a conventional superconducting magnet system 10 . The superconducting magnet system 10 includes a plurality of superconducting coils 11 , a plurality of heaters 12 , an external power source 13 , a pair of current leads 14 , a heater power source 15 and a heater trigger 16 . The superconducting coil 11 is electrically connected in series to both ends of the external power source 13 through the pair of current leads 14 . Each current lead 14 includes a copper lead 141 , a high-temperature superconducting lead 142 and a low-temperature superconducting (low-temperature superconducting, LTS) 143 connected in series. The heater 12 is electrically connected in series with the heater power supply 15 and the heater trigger 16 .

After the heater trigger 16 sends out a trigger signal, each heater 12 will heat a corresponding superconducting coil 11 to make them quench. For example, the heater trigger 16 is controlled by a control signal CS to send out a trigger signal. The control signal CS is a control signal for triggering the superconducting coil 11 , such as a quench command signal, which can be generated by a quench protection circuit. However, when the superconducting coil 11 is charging and discharging, it will be a challenge for the quench protection of the high temperature superconducting lead wire 142 itself. This is because, when the high temperature superconducting wire 142 itself undergoes a quench, the propagation speed of the quench is very slow, and it is difficult to rapidly diffuse the high temperature generated by the quench, so the high temperature generated may damage the high temperature superconducting wire 142 .

The traditional method of protecting the high-temperature superconducting wire is to design a control mechanism to directly control the external power supply, and protect the high-temperature superconducting wire by directly shutting off the external power supply. However, for the superconducting magnet system, the protection by simply turning off the power supply cannot quickly reduce the high current flowing through the high-temperature superconducting wire, so the quenching of the high-temperature superconducting wire cannot be truly realized. Protect.

Therefore, it is necessary to provide a new quench protection method for a superconducting magnet system and a high-temperature superconducting wire to at least solve the above-mentioned problems.

Contents of the invention

One or more aspects of the invention are now summarized to facilitate a basic understanding of the invention, where this summary is not an extensive overview of the invention and is not intended to identify certain elements of the invention nor to delineate its scope. . Rather, the primary purpose of the summary is to present some concepts of the invention in a simplified form before the more detailed description is presented below.

One aspect of the present invention is to provide a superconducting magnet system. The superconducting magnet system includes:

superconducting coils;

High temperature superconducting current leads;

A heater for heating the superconducting coil;

heater trigger; and

The high-temperature superconducting wire detection unit is used to detect the working state of the high-temperature superconducting wire. When the detection signal from the high-temperature superconducting wire is greater than a preset value, the high-temperature superconducting wire detection unit outputs a control signal to the A heater trigger is used to trigger the heater to work, and the preset value corresponds to the quench point or the quench critical point of the high-temperature superconducting wire.

Another aspect of the present invention is to provide another quench protection method for high-temperature superconducting wires, which is used to protect high-temperature superconducting wires in a superconducting magnet system. The method includes:

detecting the working state of the HTS lead; and

When the detection signal from the high-temperature superconducting wire is greater than a preset value, a control signal is output to heat the superconducting coil in the superconducting magnet system to make it quench, and the preset value corresponds to the quench of the high-temperature superconducting wire point or beyond the critical point.

The superconducting magnet system and the quench protection method of the high-temperature superconducting wire of the present invention can detect the state of the high-temperature superconducting wire in real time by setting the high-temperature superconducting wire detection unit, and can detect the state of the high-temperature superconducting wire before the quenching of the high-temperature superconducting wire Trigger the heater to work in time, so that the superconducting coil can be quenched. Since the quench time of the superconducting coil is very short, it can effectively prevent the quenching of the high-temperature superconducting lead itself, thereby avoiding the damage of the high-temperature superconducting lead caused by its own quench.

Description of drawings

By describing the embodiments of the present invention in conjunction with the accompanying drawings, the present invention can be better understood. In the accompanying drawings:

FIG. 1 is a schematic diagram of a conventional superconducting magnet system.

Fig. 2 is a schematic diagram of the first preferred embodiment of the superconducting magnet system of the present invention.

Fig. 3 is a control block diagram of the first preferred embodiment of the HTS wire detection unit in the superconducting magnet system of the present invention.

Fig. 4 is a schematic diagram of a second preferred embodiment of the superconducting magnet system of the present invention.

FIG. 5 is a control block diagram of a second preferred embodiment of the HTS wire detection unit in the superconducting magnet system of the present invention.

Fig. 6 is a control block diagram of the third preferred embodiment of the HTS wire detection unit in the superconducting magnet system of the present invention.

Detailed ways

Specific implementations of the present invention will be described below. It should be noted that in the process of specific descriptions of these implementations, for the sake of concise description, it is impossible for this specification to describe all the features of the actual implementations in detail. It should be understood that, in the actual implementation process of any embodiment, just like in the process of any engineering project or design project, in order to achieve the developer's specific goals and to meet system-related or business-related constraints, Often a variety of specific decisions are made, and this can vary from one implementation to another. In addition, it will be appreciated that while such development efforts may be complex and lengthy, the technology disclosed in this disclosure will be Some design, manufacturing or production changes based on the content are just conventional technical means, and should not be interpreted as insufficient content of the present disclosure.

Unless otherwise defined, the technical terms or scientific terms used in the claims and the description shall have the ordinary meanings understood by those skilled in the technical field to which the present invention belongs. "First", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "A" or "one" and similar words do not indicate a limitation of number, but mean that there is at least one. Words such as "comprises" or "comprises" and similar terms mean that the elements or items listed before "comprises" or "comprises" include the elements or items listed after "comprises" or "comprises" and their equivalent elements, and do not exclude other components or objects. Words like "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

Please refer to FIG. 2 , which is a schematic diagram of a first preferred embodiment of a superconducting magnet system (such as a magnetic resonance magnet superconducting system) 100 of the present invention. The superconducting magnet system 100 includes a number of superconducting coils 110, a number of heaters 120, an external power supply 130, a pair of current leads 140, a heater power supply 150, a heater trigger 160, a high temperature superconducting wire detection unit 170 and two voltage detector 180 . In a non-limiting embodiment, each current lead 140 includes a copper lead 1410 , a high temperature superconducting lead 1420 and a low temperature superconducting lead 1430 connected together in series. In other embodiments, besides the high temperature superconducting lead 1420 , the current lead 140 may correspondingly increase or decrease other lead parts as required, not limited to the examples given in this embodiment.

The superconducting coil 110 is electrically connected in series to both ends of the external power source 130 through the pair of current leads 140 . The heater 120 is electrically connected in series with the heater power supply 150 and the heater trigger 160 . The two voltage detectors 180 are respectively electrically coupled to the pair of high-temperature superconducting wires 1420 for real-time detection of voltage signals on the pair of high-temperature superconducting wires 1420 . The high temperature superconducting wire detection unit 170 is used to receive the voltage signals V _s1 and V _s2 detected by the voltage detector 180, and generate a corresponding control signal CS according to the voltage signals V _s1 and V _s2 to control the heater to trigger device 160. The heater trigger 160 may also receive control signals from other control units, for example, receive control signals from the quench protection circuit of the superconducting coil 110 to control its operation, which is not specifically described here.

Please refer to FIG. 3 , which is a control block diagram of the first preferred embodiment of the HTS wire detection unit 170 . In this embodiment, the HTS wire detection unit 170 includes a comparator 171 and two buffers 174 . The two buffers 174 are respectively used to receive the voltage signals V _s1 and V _s2 detected by the two voltage detectors 180 and transmit them to the two input terminals of the comparator 171 . In other implementation manners, the buffer 174 does not need to be provided, and the two input terminals of the comparator 171 can directly receive the detected voltage signals V _s1 and V _s2 . It is also possible to add other signal processing components, such as a signal amplifier, to perform preprocessing on the voltage signal before performing subsequent comparison operations, which can be specifically designed according to actual needs and not limited to the examples given in this embodiment.

The comparator 171 is used to compare the received voltage signals V _s1 and V _s2 with a preset reference voltage V _{ref_s} respectively. The reference voltage V _{ref_s} can be adjusted according to needs, for example, it can be set by an external circuit or chip, or the comparator 171 itself has the function of setting and adjusting the reference voltage.

In this embodiment, the reference voltage value V _{ref_s} satisfies: when any one of the voltage signals V _s1 and V _s2 is greater than the reference voltage value V _{ref_s} , the voltage on the corresponding high-temperature superconducting wire 1420 will rise rapidly. High, that is to say, the high temperature superconducting lead 1420 is about to be quenched or near a quenched state. That is, the reference voltage V _{ref_s corresponds} to the quench point or the quench critical point of the HTS lead 1420 . In some embodiments, the reference voltage value V _{ref_s} corresponds to about 1 μV per centimeter of the length of the high-temperature superconducting lead wire 1420 , for example, when the length of the high-temperature superconducting lead wire 1420 is 60 cm, the reference voltage value V _{ref_s} is about 60μV. In other specific implementation manners, the reference voltage value V _{ref_s} must be set according to the parameters of the HTS wire used in practice, such as the material and length of the HTS wire.

During specific operation, that is, during the charging and discharging process of the superconducting magnet system 100 , the HTS wire detection unit 170 detects the voltage signals V _s1 and V _s2 on the pair of HTS wires 1420 in real time. The comparator 171 compares the received voltage signals V _s1 and V _s2 with a preset reference voltage V _{ref_s} respectively. When any one of the voltage signals V _s1 and V _s2 is greater than the reference voltage V _{ref_s} , the comparator 171 outputs a control signal CS to control the heater trigger 160 . The heater trigger 160 triggers the heater trigger 160 to work according to the control signal CS, so that the heater 120 heats the superconducting coil 110 , and then realizes quenching of the superconducting coil 110 . Since the quench time of the superconducting coil 110 is very short, for example, one second, this can effectively prevent the high temperature superconducting lead 1420 itself from being quenched, thereby avoiding damage.

Please refer to FIG. 4 , which is a schematic diagram of a second preferred embodiment of the superconducting magnet system 100 of the present invention. Compared with the first preferred embodiment, the second preferred embodiment replaces the voltage detector 180 on each high-temperature superconducting lead 1420 with a low-temperature end temperature detector 181 and a high-temperature end temperature detector 182 . The low temperature end temperature detector 181 is arranged at the low temperature end of the corresponding high temperature superconducting wire 1420, the high temperature end temperature detector 182 is arranged at the high temperature end of the corresponding high temperature superconducting wire 1420, the low temperature end temperature detector 181 and the high temperature end The temperature detector 182 is used to detect the temperature at the corresponding position. In a non-limiting embodiment, the low-temperature end temperature detector 181 and the high-temperature end temperature detector 182 convert the detected temperature into a corresponding voltage signal output, and other embodiments can also be converted into a current signal output. The high temperature superconducting wire detection unit 170 is used to receive the voltage signals V _L1 , V _L2 and V _H1 , V _H2 output by the low temperature end temperature detector 181 and the high temperature end temperature detector 182 , and according to the voltage signals V _L1 , V _L2 and V _H1 , V _H2 generate corresponding control signals CS to control the heater trigger 160 .

Please refer to FIG. 5 , which is a control block diagram of the second preferred embodiment of the HTS wire detection unit 170 . In this embodiment, the HTS wire detection unit 170 includes two comparators 172 and 173 , four buffers 175 and 176 , and an OR element 177 . The two buffers 175 are respectively used to receive the voltage signals V _H1 and V _H2 from the two high temperature detectors 182 and transmit them to the two input terminals of the comparator 175 . The two buffers 176 are respectively used to receive the voltage signals V _L1 and V _L2 from the two low temperature detectors 181 and transmit them to the two input terminals of the comparator 176 . The comparator 172 is used to compare the received voltage signals V _H1 and V _H2 with a preset reference voltage V _{ref_H} respectively. The comparator 173 is used to compare the received voltage signals V _L1 and V _L2 with a preset reference voltage V _{ref_L} respectively. The "OR" element 177 is used to receive the signals output by the two comparators 172 and 173 and perform an OR operation on them before outputting.

In this embodiment, the reference voltage value V _{ref_H} satisfies: when any one of the voltage signals V _H1 and V _H2 is greater than the reference voltage value V _{ref_H} , the voltage on the corresponding high-temperature superconducting lead 1420 will rise rapidly. High, that is to say, the high temperature superconducting lead 1420 is about to be quenched or near a quenched state. That is, the reference voltage V _{ref_H corresponds} to the quench point or the quench critical point of the HTS lead 1420 . Similarly, the reference voltage value V _{ref_L} satisfies: when any one of the voltage signals V _L1 and V _L2 is greater than the reference voltage value V _{ref_L} , the voltage on the corresponding high-temperature superconducting lead 1420 will rise rapidly, and also That is to say, the high-temperature superconducting wire 1420 is about to be quenched or in a state close to quenching. That is, the reference voltage V _{ref_L corresponds} to the quench point or the quench critical point of the HTS lead 1420 .

In some embodiments, the low-temperature end temperature detector 181 and the high-temperature end temperature detector 182 are resistance temperature detectors (resistance-temperature-sensors, RTS). In other embodiments, other types of temperature detectors may also be used. As an example, the temperature range corresponding to the reference value V _{ref_H} is approximately 65K-77K, and the temperature range corresponding to the reference value V _{ref_L} is approximately 4K-10K. In other specific implementation manners, the reference values V _{ref_H} and V _{ref_L} must be set according to parameters of the HTS wire used in practice, such as parameters such as the material of the HTS wire.

When working specifically, that is, during the charging and discharging process of the superconducting magnet system 100, the high-temperature superconducting wire detection unit 170 detects the low-temperature and high-temperature end temperature detectors 181 and 182 on the pair of high-temperature superconducting wires 1420 in real time. The incoming voltage signals V _L1 , V _L2 and V _H1 , V _H2 . The comparator 172 compares the received voltage signals V _H1 and V _H2 with a preset reference voltage V _{ref_H} respectively. When any one of the voltage signals V _H1 and V _H2 is greater than the reference voltage value V _{ref_H} , the comparator 172 outputs a control signal CS to control the heater trigger 160 through the OR element 177 . The heater trigger 160 triggers the heater trigger 160 to work according to the control signal CS, so that the heater 120 heats the superconducting coil 110 , and then realizes quenching of the superconducting coil 110 . Similarly, the comparator 173 compares the received voltage signals V _L1 and V _L2 with the preset reference voltage V _{ref_L} respectively. When any one of the voltage signals V _L1 and V _L2 is greater than the reference voltage value V _{ref_L} , the comparator 172 outputs a control signal CS to control the heater trigger 160 through the OR element 177 . The heater trigger 160 triggers the heater trigger 160 to work according to the control signal CS, so that the heater 120 heats the superconducting coil 110 , and then realizes quenching of the superconducting coil 110 .

Please refer to FIG. 6 , which is a control block diagram of a third preferred implementation manner of the HTS wire detection unit 170 . The third preferred implementation mode is a combination of the first preferred implementation mode and the second preferred implementation mode, and the specific working principles will not be repeated here. That is to say, the voltage detector 180 and the low-temperature and high-temperature end temperature detectors 181 and 182 are used to detect the state of the high-temperature superconducting lead wire 1420 approaching the quench point, so that the high-temperature superconducting lead wire 1420 is not quenched but is about to be quenched. When quenching, the heater 120 is triggered to work in time to realize the overall quenching of the coil 110 , and then quickly reduce the current to protect the high temperature superconducting lead 1420 from damage caused by its own quenching.

Although the present invention has been described in conjunction with specific embodiments, those skilled in the art will appreciate that many modifications and variations can be made to the present invention. It is, therefore, to be realized that the intent of the appended claims is to cover all such modifications and variations as are within the true spirit and scope of the invention.

Claims (20)

1. a superconducting magnet system, is characterized in that: this superconducting magnet system comprises:

Superconducting coil;

High-temperature superconducting lead;

Heater, for heating to superconducting coil;

Heater trigger; And

High-temperature superconducting lead detecting unit, for detecting the operating state of this high-temperature superconducting lead, when being greater than preset value from the detection signal in this high-temperature superconducting lead, this high-temperature superconducting lead detecting unit exports control signal to this heater trigger, to trigger this heater work, this preset value is to should the quench point of high-temperature superconducting lead or quench critical point.

2. superconducting magnet system as claimed in claim 1, wherein this system comprises voltage detector further, and for detecting the voltage in this high-temperature superconducting lead, this detection signal is the voltage signal that this voltage detector detects.

3. superconducting magnet system as claimed in claim 2, wherein this high-temperature superconducting lead detecting unit comprises comparator, for receiving this voltage signal and comparing with this preset value, when this voltage signal is greater than this preset value, exports this control signal.

4. superconducting magnet system as claimed in claim 2, wherein the high-temperature superconducting lead of the corresponding every centimetre length of this preset value is approximately 1 μ V.

5. superconducting magnet system as claimed in claim 1, wherein this system comprises further:

Temperature end Temperature Detector, for detecting the temperature at temperature end place in this high-temperature superconducting lead; And

Low-temperature end Temperature Detector, for detecting the temperature at low-temperature end place in this high-temperature superconducting lead;

This detection signal comprises first and second signal of this temperature end Temperature Detector and the detection of low-temperature end Temperature Detector, and correspondence compares first preset value and second preset value respectively.

6. superconducting magnet system as claimed in claim 5, wherein this high-temperature superconducting lead detecting unit comprises:

First comparator, for receiving this first signal and comparing with this first preset value, when this first signal is greater than this first preset value, exports this control signal; And

Second comparator, for receiving this secondary signal and comparing with this second preset value, when this secondary signal is greater than this second preset value, exports this control signal.

7. superconducting magnet system as claimed in claim 5, the temperature range that wherein this first signal is corresponding is between 65K-77K, and temperature range corresponding to this secondary signal is between 4K-10K.

8. superconducting magnet system as claimed in claim 1, wherein this system comprises further:

Voltage detector, for detecting the voltage in this high-temperature superconducting lead;

Temperature end Temperature Detector, for detecting the temperature at temperature end place in this high-temperature superconducting lead; And

Low-temperature end Temperature Detector, for detecting the temperature at low-temperature end place in this high-temperature superconducting lead;

This detection signal comprises second and third signal of the first signal, this temperature end Temperature Detector and the low-temperature end Temperature Detector detection that this voltage detector detects, and correspondence compares first preset value, second preset value and the 3rd preset value respectively.

9. superconducting magnet system as claimed in claim 8, wherein this high-temperature superconducting lead detecting unit comprises:

First comparator, for receiving this first signal and comparing with this first preset value, when this first signal is greater than this first preset value, exports this control signal;

Second comparator, for receiving this secondary signal and comparing with this second preset value, when this secondary signal is greater than this second preset value, exports this control signal; And

3rd comparator, for receiving the 3rd signal and comparing with the 3rd preset value, when the 3rd signal is greater than the 3rd preset value, exports this control signal.

10. superconducting magnet system as claimed in claim 9, wherein this high-temperature superconducting lead detecting unit comprises OR-element further, for receiving the signal of this first to the 3rd comparator output and carrying out or calculation process.

The quench protection method of 11. 1 kinds of high-temperature superconducting lead, for the protection of the high-temperature superconducting lead in superconducting magnet system, is characterized in that: the method comprises:

Detect the operating state of this high-temperature superconducting lead; And

When being greater than preset value from the detection signal in this high-temperature superconducting lead, exporting control signal and making its quench with the superconducting coil heated in this superconducting magnet system, this preset value is to should the quench point of high-temperature superconducting lead or quench critical point.

12. methods as claimed in claim 11, wherein the step of this this high-temperature superconducting lead of detection comprises: detect the voltage in this high-temperature superconducting lead, and this detection signal is the voltage signal detected.

13. methods as claimed in claim 12, wherein this control signal is produced by a high-temperature superconducting lead detecting unit, this high-temperature superconducting lead detecting unit comprises comparator, for receiving this voltage signal and comparing with this preset value, when this voltage signal is greater than this preset value, export this control signal.

14. methods as claimed in claim 12, wherein the high-temperature superconducting lead of the corresponding every centimetre length of this preset value is approximately 1 μ V.

15. methods as claimed in claim 11, wherein the step of this this high-temperature superconducting lead of detection comprises:

Detect the temperature at temperature end place in this high-temperature superconducting lead; And

Detect the temperature at low-temperature end place in this high-temperature superconducting lead;

This detection signal comprises first and second signal that in this high-temperature superconducting lead, high temperature and low-temperature end place are detected, and correspondence compares first preset value and second preset value respectively.

16. methods as claimed in claim 15, wherein this control signal is produced by a high-temperature superconducting lead detecting unit, and this high-temperature superconducting lead detecting unit comprises:

First comparator, for receiving this first signal and comparing with this first preset value, when this first signal is greater than this first preset value, exports this control signal; And

Second comparator, for receiving this secondary signal and comparing with this second preset value, when this secondary signal is greater than this second preset value, exports this control signal.

17. methods as claimed in claim 15, the temperature range that wherein this first signal is corresponding is between 65K-77K, and temperature range corresponding to this secondary signal is between 4K-10K.

18. methods as claimed in claim 11, wherein the step of this this high-temperature superconducting lead of detection comprises:

Detect the voltage in this high-temperature superconducting lead;

Detect the temperature at temperature end place in this high-temperature superconducting lead; And

Detect the temperature at low-temperature end place in this high-temperature superconducting lead;

This detection signal comprises and detects second and third signal that in the first signal of voltage, this high-temperature superconducting lead, high temperature and low-temperature end place are detected, and correspondence compares first preset value, second preset value and the 3rd preset value respectively.

19. methods as claimed in claim 18, wherein this control signal is produced by a high-temperature superconducting lead detecting unit, and this high-temperature superconducting lead detecting unit comprises:

First comparator, for receiving this first signal and comparing with this first preset value, when this first signal is greater than this first preset value, exports this control signal;

Second comparator, for receiving this secondary signal and comparing with this second preset value, when this secondary signal is greater than this second preset value, exports this control signal; And

3rd comparator, for receiving the 3rd signal and comparing with the 3rd preset value, when the 3rd signal is greater than the 3rd preset value, exports this control signal.

20. methods as claimed in claim 19, wherein this high-temperature superconducting lead detecting unit comprises OR-element further, for receiving the signal of this first to the 3rd comparator output and carrying out or calculation process.