A superconducting coil excitation method and excitation method thereof

Abstract

The present invention provides a superconducting coil and an excitation method thereof. The superconducting coil comprises a superconducting coil body and a temperature control device. The superconducting coil body is wound by a first superconducting tape. The head and tail of the first superconducting tape are pulled out and welded together to form a first joint. The temperature control device is arranged on the first joint or the first superconducting tape so that there is a temperature difference between the first superconducting tapes on both sides of the first joint. The present invention generates a voltage in the superconducting coil body through the thermoelectric effect, thereby generating a current and a magnetic field in the superconducting coil body, realizing the excitation of the superconducting coil body, without the need for an external large power supply, with a simple structure, convenient maintenance and low cost.

Description

Technical Field

[0001] The invention relates to an excitation method of a superconducting coil and an excitation method thereof. Background Art

[0002] Superconducting materials can be widely used in large-scale power equipment due to their unimpeded high current density characteristics. With the continuous rise of green energy-saving and environmental protection industries, and the continuous improvement of superconducting tape performance, output and stability, it is generally believed that large-scale application of superconducting materials is about to come. Superconducting coils made of superconducting materials can operate in an environment without current source power supply after excitation, thereby greatly reducing the volume and weight of the entire coil and its affiliated structures. At the same time, since the superconducting coils are free of current leads, the heat load of the cryogenic system used for the operation of the superconducting coils is greatly reduced. Therefore, an important application direction of superconducting coils is to provide a stable and strong magnetic field. However, in the prior art, in order to excite the superconducting coils, an external large power supply is required to power the superconducting coils. However, the large power supply mode has the disadvantages of high price, large heat leakage, and unstable current. Summary of the invention

[0003] The present invention provides an excitation method for a superconducting coil and an excitation method thereof, which generates voltage in a superconducting coil body through thermoelectric effect, thereby generating current and magnetic field in the superconducting coil body, thereby realizing excitation of the superconducting coil body, without the need for an external large power supply, with a simple structure, convenient maintenance and low cost.

[0004] The present invention is achieved through the following technical solutions:

[0005] A superconducting coil comprises a superconducting coil body and a temperature control device. The superconducting coil body is wound by a first superconducting tape. The head and tail of the first superconducting tape are pulled out and welded together to form a first joint. The temperature control device is arranged on the first joint or the first superconducting tape so that there is a temperature difference between the first superconducting tapes on both sides of the first joint.

[0006] Furthermore, it also includes at least one pair of second superconducting tapes and multiple temperature control devices. One end of each pair of second superconducting tapes is welded together to form multiple second joints arranged from the inside to the outside. The other end of each pair of second superconducting tapes is stacked and welded together in sequence from the inside to the outside. The innermost second superconducting tape is welded to the superconducting coil body to realize the parallel connection of the first joint and each second joint. The second superconducting tapes on both sides of each second joint are provided with temperature control devices.

[0007] Furthermore, it also includes two third superconducting tapes, one end of the two third superconducting tapes are welded to form a third joint, and the other end is welded to the outermost second superconducting tape, and a heating device is provided on the third joint. The length of the third joint is greater than that of the first and second joints so that the resistance of the third joint is much smaller than that of the first and second joints, and the lengths of the first and second joints are basically the same.

[0008] Furthermore, the temperature control device includes a resistance wire wound around the first superconducting tape on at least one side of the first joint, an insulating device arranged between the resistance wire and the first superconducting tape, and a power supply connected to the resistance wire to supply power to the resistance wire to generate heat.

[0009] Furthermore, the temperature control device includes a heat conducting strip having one end arranged on one side of the first joint and a cold source or a heat source connected to the other end of the heat conducting strip, and the heat conducting strip is made of a high thermal conductivity material.

[0010] Furthermore, the superconducting surfaces of the first, second and third tapes are welded together.

[0011] Furthermore, the lengths of the first and second joints are 3-8 cm, and the length of the second joint is 10-20 cm.

[0012] The present invention is also achieved through the following technical solutions:

[0013] A method for exciting a superconducting coil comprises the following steps:

[0014] A. lowering the temperature of the superconducting coil body and the first superconducting tape;

[0015] B. Power the resistance wire with a power supply to generate Joule heat in the resistance wire, thereby generating a temperature difference on the first strip on both sides of the first joint. Due to the thermoelectric effect, the superconducting coil body can be excited.

[0016] The present invention is also achieved through the following technical solutions:

[0017] A method for exciting a superconducting coil comprises the following steps:

[0018] A. lowering the temperature of the superconducting coil body, the first, second and third superconducting tapes;

[0019] B. using a heating device to make the temperature of the second joint higher than the critical temperature of the third superconducting tape so that the second joint is in a normal state;

[0020] C. Using a power supply to supply power to each resistance wire, so that the resistance wire generates Joule heat, thereby generating a temperature difference between the two first strips on both sides of each first joint, and the excitation of the superconducting coil body can be completed due to the thermoelectric effect;

[0021] D. Disconnect the power supply, turn off the heating device, and switch the second joint to the superconducting state.

[0022] The present invention has the following beneficial effects:

[0023] 1. The present invention pulls out the head and tail of the first superconducting tape wound around the superconducting coil body and welds them together to form a first joint, and uses a temperature control device to make the superconducting tapes on both sides of the first joint have a temperature difference. Due to the thermoelectric effect of the superconducting material itself, a voltage is generated in the superconducting coil body. Since the first joint has a certain resistance, a current and a magnetic field are generated in the superconducting coil body, that is, the excitation of the superconducting coil body is realized, and no external large power supply is required to power the superconducting coil body, that is, the disadvantages of high price, large heat leakage, unstable current, etc. are avoided. In addition, the structure is simple, maintenance is convenient, and the cost is low.

[0024] 2. Multiple parallel second joints are set up, and the two second superconducting tapes forming each second joint form a closed loop with the superconducting coil body. Even if the excitation current generated by each second joint is small, the multiple parallel excitation currents will generate a larger current in the superconducting coil body, thereby generating stronger magnetism; temperature control devices are set on the second superconducting tapes on both sides of the second joints, which can control the size and direction of the current and magnetic field in the superconducting coil body.

[0025] 3. A third joint is formed by welding one end of two third superconducting tapes. The resistance of the third joint is smaller than that of the first and second joints. A heating device is arranged on the third joint to make the third joint a superconducting switch. During the excitation process, the heating device keeps the third joint in a normal state, thereby disconnecting the closed loop formed by the two third superconducting tapes and the superconducting coil body. Excitation is achieved by the first joint and / or the second joint. After the excitation is completed, the heating device keeps the third joint in a superconducting state. At this time, the resistance of the third joint is much smaller than that of the first and second joints, and is close to zero resistance, so that the current flows only in the closed loop formed by the third superconducting tape and the superconducting coil body, thereby maintaining the stability of the current and the magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described in detail below with reference to the accompanying drawings.

[0027] Figure 1 It is a schematic structural diagram of a superconducting coil embodiment 1 of the present invention.

[0028] Figure 1-1 Schematic diagram of the arrangement of resistance wires in the first embodiment of the superconducting coil of the present invention.

[0029] Figure 2 This is a schematic structural diagram of a superconducting coil embodiment 3 of the present invention.

[0030] Figure 3 Schematic diagram of the structure of the superconducting coil embodiment 4 of the present invention.

[0031] Figure 4 Schematic diagram of the arrangement of heat-conducting strips in the fifth embodiment of the superconducting coil of the present invention.

[0032] Among them, 1. superconducting coil body; 2. first superconducting tape; 3. first joint; 4. second superconducting tape; 5. second joint; 6. third superconducting tape; 7. heating device; 8. temperature control device; 81. resistance wire; 82. thermal conductive strip. DETAILED DESCRIPTION

[0033] Embodiment 1:

[0034] like Figure 1 and Figure 1-1 As shown, the superconducting coil includes a superconducting coil body 1 and a temperature control device 8. The superconducting coil body 1 is wound by a first superconducting tape 2. More specifically, the first superconducting tape 2 is a 4 mm wide BSCCO tape, and the superconducting coil body 1 is a single-wire double-pancake coil. The head and tail of the first superconducting tape 2 are pulled out and welded together to form a first joint 3. The solder used for welding is solder. The wide surface of the first superconducting tape 2 is a superconducting surface, so the wide surfaces of the two first superconducting tapes 2 are welded together. The temperature control device 8 includes a resistance wire 81 wound on the first superconducting tape 2 on one side of the first joint 3, an insulating device arranged between the resistance wire 81 and the first superconducting tape 2, and a power source connected to the resistance wire 81 to supply power to it to make it heat up. The power supply supplies power to the resistance wire 81, causing the resistance wire 81 to generate Joule heat, thereby forming a temperature difference between the first superconducting tape 2 at both ends of the first joint 3. Due to the thermoelectric effect of the superconducting material, a voltage will be generated in the superconducting coil body 1. In the closed loop formed by the superconducting coil body 1 and the first superconducting tape 2, other parts have no resistance, and only the first joint 3 has a weak resistance. Therefore, the voltage can generate current and magnetic field in the superconducting coil, thereby completing the excitation of the superconducting coil body 1.

[0035] The insulating device may be an insulating layer coated on the surface of the resistance wire 81 to prevent the resistance wire 81 from being short-circuited. The power source may be a mains supply or other power supply devices.

[0036] Embodiment 2:

[0037] The difference between this embodiment and the first embodiment is that:

[0038] Temperature control devices are provided on the first superconducting tapes on both sides of the first joint. The temperature control devices are the same as the temperature control devices in the first embodiment and can more flexibly control the temperature difference of the first superconducting tapes on both sides of the first joint, thereby flexibly controlling the generated current.

[0039] The other contents of this embodiment are the same as those of the first embodiment and will not be described again here.

[0040] Embodiment three:

[0041] The difference between this embodiment and the second embodiment is that:

[0042] like Figure 2 As shown, it also includes two pairs of second superconducting tapes 4 and four temperature control devices 8. The second superconducting tapes 4 are also 4 mm wide BSCCO tapes. One end of each pair of second superconducting tapes 4 is welded together to form two second joints 5 arranged from the inside to the outside. The other end of each pair of second superconducting tapes 4 is stacked and welded together in sequence from the inside to the outside. The other end of the innermost second superconducting tape 4 is welded to the superconducting coil body 1 to realize the first joint 3 and the parallel connection with the two second joints 5. The second superconducting tapes 4 on both sides of each second joint 5 are provided with temperature control devices 8.

[0043] The other contents of this embodiment are the same as those of the second embodiment and will not be described again here.

[0044] Embodiment 4:

[0045] The difference between this embodiment and the third embodiment is that:

[0046] like Figure 3 As shown, two third superconducting tapes 6 are also included. One end of the two third superconducting tapes 6 is welded to each other to form a third joint, and the other end is welded to the outermost second superconducting tape 4, so that the third joint is connected in parallel with the second joint 5. A heating device 7 is arranged on the third joint. The length of the third joint is greater than that of the first joint 3 and the second joint 5, so that the resistance of the third joint is much smaller than that of the first joint 3 and the second joint 5, and the length of the first joint 3 and the second joint 5 is substantially the same. The heating device 7 may be a resistance wire.

[0047] In this embodiment, the lengths of the first joint 3 and the second joint 5 are 5 cm, and the length of the second joint 5 is 15 cm.

[0048] The other contents of this embodiment are the same as those of the third embodiment and will not be described again here.

[0049] Embodiment five:

[0050] The difference between this embodiment and the first embodiment is that:

[0051] like Figure 4As shown, the temperature control device 8 includes a heat conducting strip 82 with one end arranged on one side of the first joint 3 and a cold source or a hot source connected to the other end of the heat conducting strip 82. The heat conducting strip 82 is made of a high thermal conductivity material, such as copper or aluminum. The cold source can be a refrigerator or a low-temperature refrigerant. The hot source can be copper or other structural parts connected to the room temperature environment. The superconducting coil body can be cooled or heated by the cold source or the hot source, and the superconducting coil body can be magnetized by using the temperature difference between the cold source or the hot source and the superconducting coil body.

[0052] More specifically, when the heat conductive strip 82 is connected to the refrigerator, the refrigerator temperature is lower, while the superconducting coil body temperature is initially higher than the refrigerator temperature, thus forming a temperature difference. After the temperature difference is formed, the superconducting coil body can be magnetized.

[0053] The excitation method of the superconducting coil of the first embodiment includes the following steps:

[0054] A. Immerse the superconducting coil body 1, the first superconducting tape 2, the first joint 3 and the resistance wire in liquid nitrogen at a temperature of 77K to reduce the temperature of the superconducting coil body 1 and the first superconducting tape 2, thereby entering a superconducting state.

[0055] B. Power the resistance wire with a power supply to generate Joule heat in the resistance wire, thereby generating a temperature difference on the first strip on both sides of the first joint 3. Due to the thermoelectric effect, the superconducting coil body 1 can be excited.

[0056] In this embodiment, liquid nitrogen is used for cooling. In other embodiments, other cold sources may be used for cooling, such as a refrigerator. The cooling temperature is not necessarily limited to 77K. The refrigerator can flexibly adjust the cooling temperature according to actual conditions.

[0057] The method for exciting the superconducting coil of the fourth embodiment includes the following steps:

[0058] A. Immerse the first joints 3, second joints 5 and resistance wires of the superconducting coil body 1, the first superconducting tape 2, the second superconducting tape 4 and the third superconducting tape 6 in liquid nitrogen, the temperature of which is 77K, so as to reduce the temperature of the superconducting coil body 1, the first superconducting tape 2, the second superconducting tape 4 and the third superconducting tape 6, thereby entering a superconducting state;

[0059] B. Using the heating device 7 to make the temperature of the second joint 5 higher than the critical temperature of the third superconducting tape, so that the second joint 5 is in a normal state;

[0060] C. Powering each resistance wire with a power supply to generate Joule heat in the resistance wire, thereby generating a temperature difference between the two first strips on both sides of each first joint 3. Due to the thermoelectric effect, the superconducting coil body 1 can be excited;

[0061] D. Disconnect the power supply and turn off the heating device 7 to switch the second joint 5 to the superconducting state.

[0062] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of implementation of the present invention. That is, equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the specification should still fall within the scope covered by the patent of the present invention.

Claims

1. A superconducting coil, characterized in that: The invention comprises a superconducting coil body and a temperature control device, wherein the superconducting coil body is wound by a first superconducting tape, the head and tail of the first superconducting tape are pulled out and welded together to form a first joint, and the temperature control device is arranged on the first joint or the first superconducting tape so that there is a temperature difference between the first superconducting tapes on both sides of the first joint; the invention also comprises at least one pair of second superconducting tapes and a plurality of temperature control devices, one end of each pair of second superconducting tapes is welded together to form a plurality of second joints arranged from the inside to the outside, the other end of each pair of second superconducting tapes is stacked and welded together in sequence from the inside to the outside, the innermost second superconducting tape is welded on the superconducting coil body to realize the first joint and each second joint being connected in parallel, and the second superconducting tapes on both sides of each second joint are provided with a temperature control device; the invention also comprises two third superconducting tapes, one end of the two third superconducting tapes is welded to form a third joint, and the other end is welded to the outermost second superconducting tape, a heating device is arranged on the third joint, the length of the third joint is greater than the length of the first and second joints so that the resistance of the third joint is much smaller than the resistance of the first and second joints, and the lengths of the first and second joints are substantially the same.

2. A superconducting coil according to claim 1, characterized in that: The temperature control device includes a resistance wire wound around the first superconducting tape on at least one side of the first joint, an insulating device arranged between the resistance wire and the first superconducting tape, and a power source connected to the resistance wire to supply power to the resistance wire to generate heat.

3. A superconducting coil according to claim 1, characterized in that: The temperature control device comprises a heat conducting strip with one end arranged on one side of the first joint and a cold source or a heat source connected to the other end of the heat conducting strip, and the heat conducting strip is made of a high heat conducting material.

4. A superconducting coil according to claim 1, 2 or 3, characterized in that: The superconducting surfaces of the first, second and third tapes are welded together.

5. A superconducting coil according to claim 3, characterized in that: The lengths of the first and second joints are 3-8 cm, and the length of the second joint is 10-20 cm.

6. A method for exciting a superconducting coil, characterized in that: The steps include: A. lowering the temperature of the superconducting coil body, the first, second and third superconducting tapes; B. using a heating device to make the temperature of the second joint higher than the critical temperature of the third superconducting tape so that the second joint is in a normal state; C. Using a power supply to supply power to each resistance wire, so that the resistance wire generates Joule heat, thereby generating a temperature difference between the two first strips on both sides of each first joint, and the excitation of the superconducting coil body can be completed due to the thermoelectric effect; D. Disconnect the power supply, turn off the heating device, and switch the second joint to the superconducting state.

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