Device, system and method for measuring critical current of high-temperature superconducting cable

Abstract

The invention belongs to the technical field of high-temperature superconducting, and discloses a high-temperature superconducting cable critical current measuring device, system and method, and the device, system and method are characterized in that a plurality of voltage measuring ends are arranged on a high-temperature superconducting cable, and voltage changes at different positions are monitored at the same time. When the current gradually rises to be close to or reach the critical value, the voltage change of each section can be more accurately captured and recorded, and the accuracy of critical current measurement is effectively improved. The current lead terminal is connected with the high-temperature superconducting cable, reliable and stable contact is provided between the current lead terminal and the cable, and measurement errors caused by contact resistance are reduced. The existence of the insulating bottom plate can avoid high-voltage leakage or current interference, thereby ensuring the stability and reliability of a measurement result. The reasonable arrangement of the insulating bottom plate and the current lead terminals can shield or isolate the influence of the external environment on the measurement process to a certain extent, ensure that the test environment required by the cable in a high-current state is stable, and improve the measurement accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature superconductivity, and particularly relates to a high-temperature superconducting cable critical current measurement device, system and method. Background Art

[0002] A superconducting cable refers to a conductor formed by stacking and encapsulating multiple high-temperature superconducting tapes using a certain structure and process scheme, with large current-carrying capacity and high mechanical strength. High-temperature superconducting materials have a critical temperature, critical current, and critical magnetic field far higher than those of low-temperature superconducting materials, providing a better choice for constructing high-field magnets, such as for constructing fusion reactor magnets, accelerator magnets, detector magnets, motors, etc.

[0003] Due to the limited current-carrying capacity and mechanical properties of a single high-temperature superconducting tape, in order to reduce the inductance of a large superconducting magnet and overcome the huge electromagnetic stress in the large superconducting magnet, it is necessary to encapsulate multiple high-temperature superconducting tapes into a conductor with large current-carrying capacity and high mechanical properties. A typical conductor solution is to encapsulate multiple high-temperature superconducting tapes into one body to utilize the mature low-temperature superconducting magnet manufacturing technology to manufacture large high-temperature superconducting magnets. During the process of encapsulating high-temperature superconducting tapes into a conductor, the superconducting tapes will inevitably be subjected to factors such as high temperature, which may cause the decline of the current-carrying capacity of the high-temperature superconducting tapes. Therefore, it is necessary to conduct current-carrying detection on the completed superconducting cable to feedback the critical current attenuation characteristics caused by different structures and processes to the stacked superconducting tapes.

[0004] For the critical current test of high-temperature superconducting cables, if the conventional four-wire method is used for testing, directly passing current through the entire end of the high-temperature superconducting cable and collecting voltage signals as a whole, it is very easy to cause uneven charging on each superconducting tape in the superconducting cable, resulting in current redistribution and inaccurate test results.

[0005] In the patent application "New High-Temperature Superconducting Twisted Cable Critical Current Measurement System and Measurement Method (CN117289189A)", a twisted cable critical current measurement system and measurement method are introduced. The twisted cable is directly welded inside a copper nose, and current is passed through the entire cable as a whole, unable to ensure uniform current sharing on each superconducting tape.

[0006] In addition, in the patent "A Superconducting Cable In-Field Critical Current Continuous Measurement Device and Method (CN115267625B)", a cable in-field critical current continuous measurement device and method are introduced. The current-carrying method is still to clamp the cable with two copper jaw electrodes and pass current through the cable as a whole. Although the continuous measurement of the critical current along the length of the cable can be tested, the overall structure is complex and the operation difficulty is large. Summary of the Invention

[0007] The object of the present invention is to overcome the problem of inaccurate detection of the critical current data of the above-mentioned cable, and to provide a high-temperature superconducting cable critical current measurement device, system and method.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a high-temperature superconducting cable critical current measurement device, including an insulating bottom plate, on which two current lead terminals are arranged, the two current lead terminals are arranged facing each other, a high-temperature superconducting cable is connected between the two current lead terminals, and at least two voltage measurement terminals are arranged on the high-temperature superconducting cable.

[0009] A further improvement of the present invention is that the high-temperature superconducting cable includes several layers of superconducting tapes, and all the superconducting tapes are encapsulated by soldering.

[0010] A further improvement of the present invention is that the current lead terminal is provided with a stepped connection part, the two ends of the high-temperature superconducting cable are stepped cables, and the stepped cables of the high-temperature superconducting cable are welded on different stepped connection parts of the current lead terminal.

[0011] A further improvement of the present invention is that a layered structure is formed on the end face of the current lead terminal, and all the superconducting tapes of the high-temperature superconducting cable are respectively inserted into each layer of the layered structure.

[0012] A further improvement of the present invention is that the stepped connection part of the current lead terminal is covered with a cover plate.

[0013] A further improvement of the present invention is that the voltage measurement terminal includes several copper sheets, one end of each copper sheet is fixed between adjacent superconducting tapes in the high-temperature superconducting cable by soldering, and the other ends of all the copper sheets are encapsulated in a copper block.

[0014] A further improvement of the present invention is that the upper and lower positions of each copper sheet are kept consistent, and a voltage lead is led out from the copper block.

[0015] A further improvement of the present invention is that the current lead terminal is provided with a wiring hole for connecting with an external power supply line.

[0016] A further improvement of the present invention is that the insulating bottom plate is made of epoxy resin material.

[0017] In a second aspect, the present invention provides a high-temperature superconducting cable critical current measurement system, including a liquid nitrogen tank and a high-temperature superconducting cable critical current measurement device, the high-temperature superconducting cable critical current measurement device is placed in the liquid nitrogen tank, all voltage measurement terminals are connected to a voltage acquisition meter, the two current lead terminals are respectively connected to the positive and negative poles of a DC power supply, the DC power supply is connected to a host computer, and the host computer is connected to the voltage acquisition meter; The host is used to collect the current value of the DC power supply and the voltage values of all voltage measurement terminals, and obtain the critical current of the high-temperature superconducting cable by comparing the current value with the voltage value.

[0018] A further improvement of the present invention is that the positive pole of the DC power supply is connected to the input end of the shunt, and the output end of the shunt is respectively connected to the host and the current lead terminal.

[0019] In a third aspect, the present invention provides a method for measuring the critical current of a high-temperature superconducting cable, using a system for measuring the critical current of a high-temperature superconducting cable, including the following steps: Pour liquid nitrogen into the liquid nitrogen tank to make the device for measuring the critical current of the high-temperature superconducting cable reach the required temperature; Supply power to the high-temperature superconducting cable through the DC power supply and gradually increase the current; The host collects in real time the current value and voltage value provided by the DC power supply to the high-temperature superconducting cable, as well as the voltage values of all voltage measurement terminals on the high-temperature superconducting cable, and calculates in real time the difference between the voltage value of the DC power supply and the joint resistance voltage value of the voltage measurement terminal, until the voltage value of at least one voltage measurement terminal on the high-temperature superconducting cable reaches the quench criterion standard, and the current value at this time is the critical current of the high-temperature superconducting cable.

[0020] A further improvement of the present invention is that the quench criterion standard is that the collected voltage value is greater than 1 μV / cm.

[0021] Compared with the prior art, the present invention has the following beneficial effects: A critical current measurement device for high-temperature superconducting cables according to the present invention can simultaneously monitor voltage changes at different positions by arranging a plurality of voltage measurement terminals on the high-temperature superconducting cables. When the current gradually rises to approach or reach the critical value, voltage changes in each section can be more accurately captured and recorded, thereby effectively improving the accuracy of critical current measurement. The present invention uses specially designed current lead terminals to connect with the high-temperature superconducting cables, which can provide a reliable and stable contact between the current lead terminals and the cables, reducing measurement errors caused by contact resistance. At the same time, the presence of the insulating base plate can avoid high-voltage leakage or current interference, thus ensuring the stability and reliability of the measurement results. The reasonable arrangement between the insulating base plate and the current lead terminals of the present invention can, to a certain extent, shield or isolate the influence of the external environment (such as stray electromagnetic fields, temperature fluctuations, etc.) on the measurement process, ensuring the stability of the test environment required for the cables in the high-current state and further improving the measurement accuracy. The overall structure of the present invention is relatively simple, facilitating rapid setup, disassembly, and replacement of different high-temperature superconducting cables for testing. This not only improves the work efficiency in the experimental or production site but also reduces the measurement risks caused by improper installation or operation. The device can be used for critical current measurement of high-temperature superconducting cables with different specifications and different structural forms. By flexibly adjusting the spacing and quantity of the voltage measurement terminals, it can be applied to various occasions such as research and development, factory production inspection, and technical verification in scientific research institutions, with strong versatility. In summary, the critical current measurement device for high-temperature superconducting cables can not only improve the accuracy and stability of cable critical current testing but also has high operability and flexibility in terms of structure and usage method, meeting multiple requirements in the actual application and research process of high-temperature superconducting cables.

[0022] Furthermore, the high-temperature superconducting cable of the present invention includes several layers of superconducting tapes. All superconducting tapes are encapsulated by soldering, and the multi-layer tapes are encapsulated by soldering to form an integrated structure, which can significantly improve the bending resistance, vibration resistance, and shock resistance of the cable, reduce interlayer peeling or damage during use, and also ensure that during the current-carrying process, the current can uniformly flow through each superconducting tape in the cable.

[0023] A critical current measurement system for high-temperature superconducting cables of the present invention places the entire critical current measurement device for high-temperature superconducting cables in a liquid nitrogen bath, enabling the cable to be in a stable and uniform low-temperature environment, reducing interference from external temperature fluctuations on critical current measurement. The liquid nitrogen bath provides good cooling and temperature retention capabilities, ensuring minimal thermal disturbance during the measurement process and further improving measurement stability and reliability. Multi-point voltage acquisition enables more comprehensive monitoring of the electric field distribution, allowing for a more accurate determination of the superconducting-normal transition state of the cable during current increase, thereby more precisely determining the critical current. By analyzing the process of synchronous change of current and voltage, the present invention can accurately capture the critical current immediately when the critical transition occurs, avoiding inaccurate data caused by manual switching or delayed acquisition. The DC power supply and voltage acquisition meter of the present invention are both linked with the host computer for data and control, and can be uniformly managed and calibrated through software, reducing communication delays or human reading errors between multiple devices. The cable and the measurement device are both placed in the same low-temperature environment, avoiding additional resistance, inductance, and noise interference caused by long-distance external leads. In summary, by adopting multi-point voltage acquisition and synchronous data acquisition technologies in a stable low-temperature environment, the present invention greatly improves the accuracy and stability of critical current detection for high-temperature superconducting cables, is easy to operate and can adapt to various measurement requirements, and can effectively overcome interference and errors in the previous measurement process.

[0024] A method for measuring the critical current of high-temperature superconducting cables of the present invention immerses the entire high-temperature superconducting cable in a liquid nitrogen bath, capable of keeping the cable in a constant and uniform low-temperature environment and avoiding measurement errors caused by local temperature fluctuations. During measurement, when the voltage at any measurement end reaches the quench criterion standard, the critical current can be accurately determined, realizing sensitive monitoring of the local and overall states of the cable and avoiding missed detection or misjudgment that may be caused by single-point sampling. During the process of gradually increasing the current, the system can compare the current and voltage data in real time. When the voltage value touches the quench criterion, the current at that moment is immediately determined as the critical current, preventing data deviation caused by human intervention or delayed acquisition. Automated data communication and monitoring are realized between multiple measurement ends and the host computer, eliminating the need for cumbersome manual measurement and recording, and greatly reducing the operation difficulty and error risk. The present invention is also applicable to the critical current test of similar superconducting elements or devices, and has good versatility and popularization value. In conclusion, the present invention can better overcome the problem of inaccurate data caused by factors such as susceptibility to temperature fluctuations, limited measurement points, and human errors in traditional measurement methods, and significantly improve the reliability, repeatability, and accuracy of critical current measurement. Description of the Drawings

[0025] Figure 1 It is a structural diagram of a critical current measurement device for high-temperature superconducting cables; Figure 2 It is a structural diagram of a stepped connection part in a critical current measurement device for high-temperature superconducting cables; Figure 3 is Figure 1 a partial enlarged view of region M therein; Figure 4 is a system diagram of a critical current measurement system for high-temperature superconducting cables; Figure 5 is a structural diagram of Example 5; Figure 6 is Figure 5 a partial enlarged view of region N therein; Among them, 1. current lead terminal; 2. high-temperature superconducting cable; 3. voltage measurement terminal; 4. insulating base plate; 5. liquid nitrogen tank; 6. voltage acquisition meter; 7. DC power supply; 8. host; 9. shunt; 101. wiring hole; 102. cover plate; 103. bolt; 104. bolt; 201. superconducting tape; 202. solder; 301. copper sheet; 302. copper block. Specific embodiments

[0026] To further understand the content of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are only for explaining the present invention and not for limiting it.

[0027] Example 1: Referring to Figure 1 , a critical current measurement device for high-temperature superconducting cables includes an insulating base plate 4, on which two current lead terminals 1 are provided. The two current lead terminals 1 are arranged facing each other, and a high-temperature superconducting cable 2 is connected between the two current lead terminals 1. At least two voltage measurement terminals 3 are provided on the high-temperature superconducting cable 2.

[0028] Preferably, the insulating base plate 4 is made of epoxy resin material.

[0029] Example 2: Referring to Figure 3 , on the basis of the above embodiment, the high-temperature superconducting cable 2 is further limited. Specifically, the high-temperature superconducting cable 2 includes several layers of superconducting tapes 201, and all the superconducting tapes 201 are encapsulated by solder 202.

[0030] In this embodiment, after multiple layers of superconducting tapes are stacked, the superconducting cross-section increases, which can improve the total current-carrying capacity of the cable. The solder encapsulation makes the layers of tapes in close contact, which can reduce the contact resistance between layers, improve the current uniform distribution between superconducting layers, and thus improve the critical current performance and stability of the overall cable.

[0031] Example 3: Referring to Figure 2, based on the above embodiments, the first embodiment of the connection method between the current lead terminal 1 and the high-temperature superconducting cable 2 is provided in this embodiment. Specifically, a stepped connection portion is provided on the current lead terminal 1, and both ends of the high-temperature superconducting cable 2 are stepped cables, and the stepped cables of the high-temperature superconducting cable 2 are welded to different stepped connection portions of the current lead terminal 1.

[0032] Each of the multi-layer superconducting tapes 201 in this embodiment has an independent welding contact surface, which reduces the mutual shielding or overlapping between the tapes, avoids local overcurrent caused by single-point concentrated connection, can effectively reduce the contact resistance and thermal load at a single contact point, and the overall current distribution is more uniform, thereby improving the critical current utilization rate and measurement accuracy of the cable. The connection portion of the current lead terminal 1 adopts a stepped connection portion, so that each layer of tape can form a reliable metal contact with the current lead terminal, reducing the contact resistance between the tapes and between the tape and the terminal; a lower contact resistance also means that when passing a large current, the heat generation at the joint is lower, which helps to maintain the superconducting state and avoid quenching caused by local overheating. The method of welding each layer of tape of the high-temperature superconducting cable by using a stepped connection portion in this embodiment not only optimizes the electrical and thermal properties of the multi-layer tape, but also brings obvious improvements in mechanical stability and maintenance operability, providing a more reliable connection method for the critical current measurement and practical application of the high-temperature superconducting cable.

[0033] Embodiment 4: See Figure 1 , based on the above embodiments, a new structure is added in this embodiment. A cover plate 102 is covered on the stepped connection portion of the current lead terminal 1 to ensure the effective electrical connection of the high-temperature superconducting cable 2. The cover plate 102 is fixed on the current lead terminal 1 by bolts 103. The materials of the current lead terminal 1 and the cover plate 102 are both T2 copper or oxygen-free copper.

[0034] The cover plate 102 of this embodiment can effectively cover the solder joints on the stepped connection part and the exposed part of the superconducting strip 201, preventing it from being knocked, squeezed or damaged by other external forces during assembly, transportation or use. At the same time, it reduces the pollution of the solder layer and the surface of the strip by dust, debris, etc. in the environment, and extends the service life of the connection part. After being fixed by bolts 103, the cover plate 102 can, to a certain extent, apply and maintain an appropriate pressing force on the welding layer between the strip and the current lead terminal, reducing the risk of loosening or delamination of the multi-layer strip under conditions such as thermal cycling and mechanical vibration, ensuring good contact between each layer of the strip and the current lead terminal, and maintaining a low contact resistance and a stable current transmission channel. The structure of the cover plate 102 can, to a certain extent, block the influence of external environmental factors such as humidity and oxidation on the welding layer and the strip, reducing phenomena such as oxidation and corrosion of the solder joints during long-term use. For the local electromagnetic field disturbances that may occur during high-current transmission, it can also play a certain role in shielding or buffering.

[0035] Embodiment 5: See Figure 5 and Figure 6 , based on the above embodiment, this embodiment provides a second embodiment for the connection method of the current lead terminal 1 and the high-temperature superconducting cable 2. Specifically, a layered structure is provided on the end face of the current lead terminal 1, and all the superconducting strips 201 of the high-temperature superconducting cable 2 are respectively inserted into each layer of the layered structure.

[0036] When installing the high-temperature superconducting cable, only need to insert the end strips of the high-temperature superconducting cable into the layers of the copper terminal respectively and use solder for encapsulation; in this way, it can ensure the uniform current sharing of the superconducting strips in the high-temperature superconducting cable, ensuring that there will be no local overload or current concentration phenomenon during overall transmission, thereby improving the accuracy of critical current measurement. Also ensure that the lengths of the superconducting strips in the high-temperature superconducting cable are the same, avoiding electrical performance mismatches caused by differences in strip lengths, and further ensuring the uniform distribution and stability of the current. The layered structure can provide stable physical support. After each layer is inserted and then encapsulated with solder, a firm and reliable connection is formed, greatly reducing the contact resistance and enhancing the overall mechanical stability and anti-vibration ability. This embodiment enables the superconducting strips in each layer of the high-temperature superconducting cable to achieve the best match in physical position and electrical parameters, ensuring both uniform current sharing and connection quality and assembly efficiency, thereby further improving the overall performance and reliability of the high-temperature superconducting cable critical current measurement system.

[0037] Embodiment 6: See Figure 3, on the basis of the above embodiment, the voltage measurement terminal 3 is further defined. Specifically, the voltage measurement terminal 3 includes a plurality of copper sheets 301. One end of each copper sheet 301 is fixed between adjacent superconducting tapes 201 in the high-temperature superconducting cable 2 by soldering. The other ends of all the copper sheets 301 are encapsulated in a copper block 302. The upper and lower positions of each copper sheet 301 are kept consistent, and a voltage lead is led out from the copper block 302.

[0038] During the encapsulation process, the copper sheets 301 are placed between the superconducting tapes 201, and it is ensured that the positions of the copper sheets 301 at the voltage signal acquisition points are consistent after encapsulation. After the high-temperature superconducting cable is encapsulated, the exposed copper sheets 301 are integrally encapsulated together by the copper block 302.

[0039] In this embodiment, the copper sheets 301 are accurately placed between the superconducting tapes 201 and their positions are unified after encapsulation, so that all voltage signal acquisition points are kept consistent, ensuring that the collected voltage signals have higher representativeness and comparability. A firm and uniform contact is formed between the copper sheets 301 and the superconducting tapes 201. After being integrally encapsulated by the copper block, the fluctuation of the contact resistance caused by poor contact or position deviation is reduced, thereby improving the stability and accuracy of signal acquisition. In this embodiment, through unified encapsulation, all the copper sheets 301 are integrated together as the output terminals of the voltage measurement terminal 3, which can effectively reduce the local errors and noises generated by a single measurement terminal and enhance the signal consistency of the entire system. The copper block 302 can not only integrally encapsulate the exposed copper sheets 301 to form a solid structure, but also shield external environmental interferences (such as vibration, moisture and dust) to a certain extent, protect the voltage acquisition points and extend the service life. In summary, this embodiment can effectively ensure the stability and accuracy of the voltage signal acquisition of the high-temperature superconducting cable, while taking into account the mechanical protection and production standardization requirements, and providing a more reliable voltage acquisition scheme for the critical current measurement.

[0040] Embodiment 7: See Figure 1 , on the basis of the above embodiment, the specific structure of the current lead terminal 1 is further defined. Specifically, the current lead terminal 1 and the insulating base plate 4 are tightly connected together by bolts 104; a wiring hole 101 is opened on the current lead terminal 1, and the wiring hole 101 is connected to the power line of the DC power supply for passing current through the high-temperature superconducting cable 2.

[0041] In this embodiment, the current lead terminal 1 is firmly fixed on the insulating base plate 4 by bolts 104, which can effectively prevent the displacement or loosening of the current lead terminal during experiments or operations due to vibration, temperature changes, or mechanical shocks, enhancing the overall stability. After mechanical fixation, the contact interface is closer, reducing the instability caused by the fretting effect (the change of contact resistance due to small displacements), improving the resistance stability during the current-carrying process, and ensuring the measurement accuracy. The power cord of the DC power supply is directly connected through the wiring hole 101, which can ensure sufficient contact area and reduce the problems of local overheating or resistance instability caused by poor contact. This embodiment significantly improves the mechanical stability, current transmission efficiency, assembly convenience, and environmental adaptability of the entire measurement system, thereby further enhancing the accuracy and reliability of the critical current measurement of high-temperature superconducting cables.

[0042] Embodiment 8: See Figure 4 , a critical current measurement system for high-temperature superconducting cables, including a liquid nitrogen tank 5. The critical current measurement device for high-temperature superconducting cables is placed inside the liquid nitrogen tank 5. All voltage measurement terminals 3 are connected to a voltage acquisition meter 6. Two current lead terminals 1 are respectively connected to the positive and negative poles of a DC power supply 7. The DC power supply 7 is connected to a host 8, and the host 8 is connected to the voltage acquisition meter 6. The host 8 is used to collect the current value of the DC power supply 7 and the voltage values of all voltage measurement terminals 3, and the critical current of the high-temperature superconducting cable is obtained by comparing the current value with the voltage value. The positive pole of the DC power supply 7 is connected to the input end of a shunt 9, and the output end of the shunt 9 is respectively connected to the host 8 and the current lead terminal 1.

[0043] The shunt 9 of this embodiment can shunt the large current output by the DC power supply 7 in proportion, and a part of the current is directly sent to the high-temperature superconducting cable measuring device, while the other part is transmitted to the host 8 after passing through the shunt. The host can collect and calibrate the current value more accurately based on the proportional relationship of the shunt, thereby improving the accuracy of the overall measurement. By sending the current signal to the host 8 and the current lead terminal 1 at the same time through the shunt 9, a better correspondence between the host and the actual current supply can be achieved, ensuring that when collecting current and voltage data, the two can be synchronously compared, reducing the error caused by signal delay or inconsistent collection. The shunt of this embodiment can isolate the large current DC power supply from the measurement system, reduce the electromagnetic interference that may be generated when the DC power supply is running at high load, and make the current signal collected by the host 8 more stable, thereby further ensuring the accurate detection of critical current data. The shunt 9 makes the entire current measurement path more standardized, and the fixed shunt ratio of the shunt facilitates system calibration, enhances the consistency and repeatability of data measurement, and thus improves the reliability of critical current detection of high-temperature superconducting cables. In summary, this embodiment can effectively overcome the problem of inaccurate current collection in traditional measurements by introducing a shunt 9 at the positive pole of the DC power supply 7 and connecting its output to the host 8 and the current lead terminal 1 respectively, and achieve more accurate, stable and synchronous current and voltage data collection, thereby significantly improving the accuracy and reliability of critical current measurement of high-temperature superconducting cables.

[0044] Embodiment 9: A method for measuring critical current of a high-temperature superconducting cable comprises the following steps: Step 1: Pour liquid nitrogen into the liquid nitrogen tank 5 to make the high-temperature superconducting cable critical current measuring device reach the required temperature.

[0045] Step 2: supply power to the high temperature superconducting cable 2 through the DC power supply 7 and gradually increase the current.

[0046] Step three, the host 8 collects in real time the current value and voltage value provided by the DC power supply 7 to the high-temperature superconducting cable 2, as well as the voltage values ​​of all voltage measuring terminals 3 on the high-temperature superconducting cable 2, and calculates in real time the difference between the voltage value of the DC power supply 7 and the voltage value of the voltage measuring terminal 3 until the voltage value of at least one voltage measuring terminal 3 on the high-temperature superconducting cable 2 reaches the quench criterion standard, the quench criterion being that the collected voltage value is greater than 1 μV / cm, and the current current value is the critical current of the high-temperature superconducting cable 2.

[0047] In this embodiment, a liquid nitrogen bath 5 is used to ensure that the high-temperature superconducting cable 2 is in a constant low-temperature state, avoiding unstable superconducting performance caused by temperature fluctuations, thus making the measurement process more accurate. In this embodiment, voltage signals are collected in real time from multiple voltage measurement terminals 3 provided on the high-temperature superconducting cable to ensure that signals are captured in a timely manner when a local quench occurs, avoiding the situation where local changes may be missed in single-point measurement. The host computer 8 in this embodiment collects the current value provided by the DC power supply 7 and the voltage values of each voltage measurement terminal 3 in real time, and can accurately capture the critical point at which the superconducting cable changes from the superconducting state to the normal state, reducing data lag and human error. The quench criterion set in this embodiment is that the collected voltage value is greater than 1 μV / cm, which provides an objective and unified standard for the determination of the critical current of the superconducting cable, ensuring the consistency and comparability of data in different measurement processes. In this embodiment, by gradually increasing the current, the relationship between the current and voltage changes can be accurately monitored to ensure no sudden changes during the transition process, further improving the accuracy and repeatability of the critical current measurement. In summary, by controlling the temperature environment, implementing multi-point real-time collection, and using a unified quench criterion, this measurement method significantly improves the detection accuracy, stability, and reliability of the critical current of high-temperature superconducting cables.

[0048] The present invention can uniformly flow through each superconducting tape to obtain more accurate cable critical current data. And by welding copper sheets on each superconducting tape to collect voltage signals, the accuracy and stability of signal collection are ensured. The overall structure is simple, easy to operate, and the processing difficulty of the test tooling is small.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A device for measuring critical current of a high-temperature superconducting cable, characterized in that: The invention comprises an insulating base plate (4), two current lead terminals (1) are arranged on the insulating base plate (4), the two current lead terminals (1) are arranged facing each other, a high-temperature superconducting cable (2) is connected between the two current lead terminals (1), and at least two voltage measuring terminals (3) are arranged on the high-temperature superconducting cable (2).

2. A high-temperature superconducting cable critical current measuring device according to claim 1, characterized in that: The high-temperature superconducting cable (2) comprises several layers of superconducting tapes (201), and all the superconducting tapes (201) are packaged by solder (202).

3. A device for measuring critical current of a high-temperature superconducting cable according to claim 2, characterized in that: The current lead terminal (1) is provided with a stepped connection portion, both ends of the high-temperature superconducting cable (2) are stepped cables, and the stepped cables of the high-temperature superconducting cable (2) are welded to different stepped connection portions of the current lead terminal (1).

4. A device for measuring critical current of a high-temperature superconducting cable according to claim 2, characterized in that: A layered structure is provided on the end surface of the current lead terminal (1), and all superconducting tapes (201) of the high-temperature superconducting cable (2) are respectively inserted between each layer of the layered structure.

5. A device for measuring critical current of a high-temperature superconducting cable according to claim 3, characterized in that: The stepped connection portion of the current lead terminal (1) is covered with a cover plate (102).

6. A device for measuring critical current of a high-temperature superconducting cable according to claim 2, characterized in that: The voltage measurement end (3) comprises a plurality of copper sheets (301), one end of each copper sheet (301) being fixed between adjacent superconducting tapes (201) in the high-temperature superconducting cable (2) by soldering, and the other ends of all the copper sheets (301) being encapsulated in a copper block (302).

7. A device for measuring critical current of a high-temperature superconducting cable according to claim 6, characterized in that: The upper and lower positions of each copper sheet (301) remain consistent, and voltage leads are led out from the copper block (302).

8. A device for measuring critical current of a high-temperature superconducting cable according to claim 1, characterized in that: The current lead terminal (1) is provided with a wiring hole (101) for connecting to an external power line.

9. A device for measuring critical current of a high-temperature superconducting cable according to claim 1, characterized in that: The insulating base plate (4) is made of epoxy resin material.

10. A high-temperature superconducting cable critical current measurement system, characterized in that: The invention comprises a liquid nitrogen tank (5) and a high-temperature superconducting cable critical current measuring device as claimed in any one of claims 1 to 9, wherein the high-temperature superconducting cable critical current measuring device is placed in the liquid nitrogen tank (5), all voltage measuring ends (3) are connected to a voltage acquisition meter (6), two current lead terminals (1) are respectively connected to the positive and negative poles of a direct current power supply (7), the direct current power supply (7) is connected to a host (8), and the host (8) is connected to the voltage acquisition meter (6); The host (8) is used to collect the current value of the DC power supply (7) and the voltage values ​​of all voltage measurement terminals (3), and obtain the critical current of the high-temperature superconducting cable by comparing the current value with the voltage value.

11. A high temperature superconducting cable critical current measurement system according to claim 10, characterized in that: The positive electrode of the DC power supply (7) is connected to the input end of the shunt (9), and the output end of the shunt (9) is connected to the host (8) and the current lead terminal (1) respectively.

12. A method for measuring critical current of a high-temperature superconducting cable, characterized in that: A high-temperature superconducting cable critical current measurement system according to any one of claims 10 to 11 comprises the following steps: Pour liquid nitrogen into the liquid nitrogen tank (5) to make the critical current measuring device of the high-temperature superconducting cable reach the required temperature; Supplying power to the high temperature superconducting cable (2) through a direct current power supply (7) and gradually increasing the current; The host (8) collects in real time the current value and voltage value provided by the direct current power supply (7) to the high-temperature superconducting cable (2), as well as the voltage values ​​of all voltage measuring terminals (3) on the high-temperature superconducting cable (2), and calculates in real time the difference between the voltage value of the direct current power supply (7) and the voltage value of the joint resistance of the voltage measuring terminal (3), until the voltage value of at least one voltage measuring terminal (3) on the high-temperature superconducting cable (2) reaches the quench criterion standard, and the current current value is the critical current of the high-temperature superconducting cable (2).

13. A method for measuring critical current of a high temperature superconducting cable according to claim 12, characterized in that: The quench criterion is that the collected voltage value is greater than 1μV / cm.

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