CN103578741B - The interchanging method of a kind of two superconducting tape magnetic plugs in parallel coiling - Google Patents

Abstract

The invention belongs to the field of superconducting engineering applications, in particular to a transposition method for winding a spiral coil with parallel superconducting strips. The number of said superconducting strips is at least two, and the transposition method includes the following steps: Step 1: After the two superconducting strips are stacked up and down, they are wound along the top of one axial side of the coil frame; Step 2: when winding When reaching the 1/4 position of the axial height of the bobbin, transpose for the first time; Step 3: After the two superconducting strips are overlapped up and down again, continue to wind backward along the axial direction of the bobbin; Step 4: When winding When reaching the position of 3/4 of the axial height of the bobbin, transpose for the second time; Step 5: After the two superconducting strips overlap up and down again, wrap another layer of insulating material on the completed winding layer; Step 6: Determine whether the number of winding layers of the superconducting tape is equal to the set value, if not, repeat steps 1-5, otherwise, stop winding. The invention is beneficial to increase the capacity of the superconducting coil and enhance the stability of the superconducting coil.

Description

A Transposition Method for Winding Two Parallel Superconducting Tape Spiral Coils

technical field

The invention belongs to the field of superconducting engineering applications, and in particular relates to a transposition method for winding two superconducting strip material spiral coils in parallel.

Background technique

The application of superconducting and strong electricity is a very important aspect in the application of superconducting technology, and superconducting coils, as the key technology for strong electricity applications, are the core components of many superconducting power devices, such as superconducting magnets and superconducting generators , Superconducting motors, superconducting transformers, superconducting current limiters, etc.

Generally, there are two winding methods for high-temperature superconducting coils: solenoid coil and double pie coil. Since the double pie coil requires two single pies to be welded in series, contact resistance is unavoidable. The current passing through the superconducting coil is very large, and the loss is proportional to the square of the current, and the contact resistance will cause a large loss in the coil. The solenoid coil does not need to be welded inside, has no contact resistance, has less loss, and is economical.

Due to the limited current-carrying capacity of a single strip, it cannot meet the requirements of large-capacity power equipment. When the current in the coil is large, it is necessary to use multiple parallel superconducting strips to wind the coil. When alternating current is passed through the coil, or when direct current is passed through for excitation and demagnetization, it is easy to generate circulating current in parallel strips due to unbalanced magnetic coupling. In addition, if the parallel strips are not transposed, it is also easy to cause circulation because of the different magnetic field environments. Due to the low impedance characteristics of superconducting strips, when the strips are connected in parallel without transposition, the circulating current caused by the leakage potential induced in each strip is quite large. In the parallel strips, it is possible to cause a part of the strips to have a negative current-carrying current, a part of the strips to have a current that exceeds a critical value and quench, and a part of the strips to have almost no current-carrying. When the coil is running, it is hoped that the current is evenly distributed in the parallel superconducting strips to achieve inductance balance, so the parallel strips must be transposed.

High-temperature superconducting materials are oxide ceramics. Compared with ordinary strips, high-temperature superconducting strips are very brittle and have poor mechanical properties. Excessive bending and twisting will seriously damage the electromagnetic properties of the strip. In addition, the superconducting strip has a large aspect ratio, generally greater than 20, which also makes it difficult for the strip to be transposed. When winding a solenoid coil, from a technical point of view, the superconducting tape cannot be transposed like a conventional conductor, and there is no good transposition method suitable for the superconducting tape at present.

In addition, realizing transposition of superconducting strips is also of practical significance for high and low temperature superconductor compound winding coils. Superconductors include high temperature superconductors and low temperature superconductors. Due to the cheap price of low-temperature superconducting materials, the current practical superconducting magnets are still mainly low-temperature superconducting magnets. However, due to the narrow transition temperature of low-temperature superconductors, high n value, small working temperature range, high thermal conductivity, fast quench propagation speed, and small minimum quench energy, traditional low-temperature superconducting magnets can be used under small mechanical and temperature disturbances. will rapidly transition from the superconducting state to the normal state. However, high-temperature superconductors have a wide transition temperature, low n value, large operating temperature range, low thermal conductivity, slow quench propagation speed, and large minimum quench energy, which make high-temperature superconducting magnets strong against mechanical and temperature interference. The use of high and low temperature superconducting tape composite winding coils can combine the advantages of both, so that superconducting magnets (especially superconducting magnets with a magnetic field higher than 10T) can run more stably than pure low temperature superconducting magnets and high temperature superconducting magnets , more efficient and safer.

Contents of the invention

The purpose of the present invention is to solve the problem of transposition of two parallel superconducting strip spiral coils described in the background technology, and realize complete transposition, and achieve the effects of inductance balance and current sharing, and propose a Transposition method for parallel superconducting tape coil winding.

A transposition method for winding two superconducting strip material spiral coils in parallel, the transposition method comprises the following steps:

Step 1: After the two superconducting strips overlap up and down, start to wind seamlessly and evenly at the set angle along the top of the axial side of the coil bobbin;

Step 2: When the two superconducting tapes are wound to 1/4 of the axial height of the coil frame, the superconducting tape on the upper layer is directly connected to the next winding position, and the superconducting tape on the lower layer Sequentially make one more turn and place on the upper layer of another superconducting strip to realize the first transposition of the two superconducting strips;

Step 3: After the first transposition of the two superconducting strips is completed, the two superconducting strips overlap again up and down, and continue to wind backward along the axial direction of the coil frame;

Step 4: When winding to the 3/4 position of the axial height of the bobbin, the superconducting tape on the upper layer is directly connected to the next winding position, and the superconducting tape on the lower layer is wound one more time. On the upper layer of another superconducting strip, realize the second transposition of two superconducting strips;

Step 5: After the second transposition of the two superconducting strips is completed, the two superconducting strips are overlapped again and wound to the top of the other side along the axial direction of the coil skeleton to complete the winding of one winding layer. A layer of insulating material is wound on the winding layer;

Step 6: Determine whether the number of winding layers of the superconducting tape is equal to the set value, if not, repeat steps 1-5, otherwise, stop winding, and complete a spiral coil winding of two superconducting tapes in parallel.

The coil frame is a solenoid coil.

The two superconducting strips are high temperature superconducting strips.

One of the two superconducting strips is a low-temperature superconducting strip, and the other is a high-temperature superconducting strip.

Beneficial effects of the present invention: the present invention provides a transposition method for parallel superconducting strip spiral coil winding, which can realize complete transposition, achieve the effect of inductance balance and current sharing, and is beneficial to improve the superconducting coil capacity, enhance the stability of the superconducting coil. It can be applied to superconducting coils, superconducting magnets, superconducting generators, superconducting motors, superconducting transformers, superconducting current limiters and other superconducting electrical equipment with superconducting coils as core components.

Description of drawings

Fig. 1 is the transposition method of the coil winding of two superconducting tapes in parallel in an embodiment of the present invention;

(a) Schematic diagram of the first transposition of two superconducting tapes when the number of winding layers is one;

(b) Schematic diagram of the second transposition of two superconducting tapes when the number of winding layers is one;

(c) When the number of winding layers is one, the schematic diagram of two superconducting tapes being wound on this layer;

Fig. 2 is a schematic cross-sectional view of a solenoid coil wound by the present invention;

In the figure, 11-superconducting strip 1, 12-superconducting strip 2, 13-coil skeleton, 21-insulating material.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific examples.

When the coils are wound in parallel, if the transposition is not performed, the inductance of the outer strip is smaller than that of the inner strip due to the different magnetic fields, that is, L _outside < L _inside .

Since in a superconducting strip, it can be considered that the strip resistance during operation: R≈0;

Strip reactance: X=ωL;

The total impedance of the strip Z=R+jX≈jωL;

Strip current $I=\frac{V}{\mathrm{j\&omega;L}};$

Then the electric current of the strip that is positioned at the outside is greater than the strip of the _inside , that is, I is _outside >I;

It can be seen that if there is no transposition, the current distribution of the parallel strips will be uneven, which will lead to small external inductance and large current. When the external strips carry more than the critical current, it will cause the external strips to quench or even burn out, and all the current will be transferred. To the internal strip, and then cause the internal strip to flow, and then quench and burn.

After the strip is transposed, the length of the strip and the magnetic field are the same, L _outside = L _inside , so that I _outside = I _inside , to achieve the effect of current sharing. At the same time, the method of transposition avoids welding, which also avoids the occurrence of contact resistance and reduces loss.

Figure 1(a) is a schematic diagram of the first transposition of two superconducting strips when the number of winding layers is one, and the two strips are connected in parallel to wind the coil skeleton evenly according to the set angle. Before the first transposition, the superconducting strips Material 1 is located on the upper layer, and superconducting tape 2 is located on the lower layer. When reaching the 1/4 position of the axial height of the bobbin, perform the first transposition. When transposition, the superconducting tape 1 on the upper layer does not continue to be wound sequentially, but is directly connected to the next winding position, and the superconducting tape 2 is wound sequentially along the axial direction of the coil skeleton, which is more than that of the superconducting tape 1. After one turn, it is pressed on the top of the superconducting strip 1, and then the two superconducting strips continue to be wound backwards, thereby realizing the first transposition. Due to the large diameter of the superconducting coil, which is much different from the width of the superconducting strip, the winding angle is very small, and the torsion of the superconducting strip is very small when it is directly connected to the next position. When the superconducting strip 2 is wound one more time, such a transposition method can avoid excessive bending and twisting of the superconducting strip by the ordinary transposition method, prevent damage to the mechanical properties of the superconducting strip, and make the winding The solenoid coil is more stable. After the first transposition, the superconducting strip 2 is located on the upper layer, and the strip 1 is located on the lower layer of the superconducting strip.

Figure 1(b) Schematic diagram of the second transposition of two superconducting strips when the number of winding layers is one; before the second transposition, superconducting strip 2 is located on the upper layer, and superconducting strip 1 is located on the lower layer. When winding to 3/4 of the axial height of the bobbin, carry out the second transposition, and the transposition method is the same as the first transposition. After the second transposition, the superconducting tape 1 is located on the upper layer, and the superconducting tape 2 is located on the lower layer.

Figure 1(c) When the number of winding layers is one, the schematic diagram of two superconducting tapes being wound on this layer; in the first 1/4 part and the rear 1/4 part of the axial height of the bobbin, each layer of superconducting tape The materials 1 are all located on the upper layer; in the middle 1/2 part of the axial height of the coil bobbin, each layer of superconducting tape 2 is located on the upper layer.

Figure 2 is a cross-sectional view of the wound solenoid coil. During the winding process of the solenoid coil, in order to realize transposition, the two superconducting strips are wound one more time, the inductance of the parallel superconducting strips used is basically the same, and the circulating current is very small.

The invention achieves the purpose of transposition by winding the superconducting strip on the lower layer one more time and placing it on the upper layer, thus solving the problem that the superconducting strip cannot be transposed by the conventional direct transposition method, and realizes Complete transposition can achieve the effect of inductance balance and current sharing, which is beneficial to increase the capacity of the superconducting coil and enhance the stability of the superconducting coil.

Claims (4)

1. an interchanging method for parallel connection two superconducting tape magnetic plugs coiling, is characterized in that, this interchanging method comprises the following steps:

Step 1: after two upper and lower overlaps of superconducting tape, the top, axial side along coil rack starts by the seamless uniform winding of set angle;

Step 2: when two superconducting tapes are wound into 1/4 position of coil rack axial height, the superconducting tape being positioned at upper strata is directly jumped to next circle winding position, the superconducting tape order being positioned at lower floor is many around a circle, be placed in the upper strata of another root superconducting tape, realize the first time transposition of two superconducting tapes;

Step 3: after two superconducting tapes complete first time transposition, two superconducting tapes are again overlapping up and down, and the axis along coil rack continues to be wound around;

Step 4: when being wound into 3/4 position of coil rack axial height, the superconducting tape being positioned at upper strata is directly jumped to next circle winding position, the superconducting tape being positioned at lower floor is many around a circle, is placed in the upper strata of another root superconducting tape, realizes the second time transposition of two superconducting tapes;

Step 5: after two superconducting tapes complete second time transposition, two superconducting tapes are again overlapping up and down, and the axis along coil rack is wound into opposite side top, completes the winding of a winding layer, and the winding layer completed is wound around one deck insulating material again;

Step 6: judge that whether superconducting tape winding layer number is equal with set point, if not etc., repeat step 1-5, otherwise, stop being wound around, complete a kind of two superconducting tape magnetic plugs coiling in parallel.

2. the interchanging method of a kind of two superconducting tape magnetic plugs in parallel coiling according to claim 1, is characterized in that, described coil rack is magnetic plug skeleton.

3. the interchanging method of a kind of two superconducting tape magnetic plugs in parallel coiling according to claim 1, is characterized in that, described two superconducting tapes are belt material of high temperature superconduct.

4. the interchanging method of a kind of two superconducting tape magnetic plugs in parallel coiling according to claim 1, is characterized in that, described two superconducting tapes one are low-temperature superconducting band, and another root is belt material of high temperature superconduct.