A rapid charging structure and method for a superconducting non-insulated magnet

Abstract

The present invention discloses a rapid charging structure and a charging method for a superconducting non-insulated magnet, which relates to the technical field of superconducting magnet charging. By placing a mutual inductance coil inside the superconducting magnet and energizing it, an induced current is generated in the superconducting magnet by using the mutual inductance phenomenon, thereby improving the charging speed of the superconducting magnet; the mutual inductance coefficient between the mutual inductance coil and the superconducting magnet is negative; the charging method of the rapid charging structure of the superconducting non-insulated magnet of the present invention generates an induced current in the superconducting magnet by setting a mutual inductance coil and energizing it, thereby improving the charging speed of the superconducting magnet; its basic principle is to use the induced magnetic field of the mutual inductance coil to cancel the induced magnetic field of the superconducting magnet, thereby reducing the induced electromotive force of the superconducting magnet, reducing the resistance to the current, and finally realizing the improvement of the charging speed.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting magnet charging, and specifically to a rapid charging structure and method for a superconducting non-insulated magnet. Background Art

[0002] Superconducting magnets have many applications in fields such as medical treatment, maglev, and high-energy physics. Non-insulated magnets have a strong over-current carrying capacity and can generate a strong magnetic field. Compared with superconducting magnets with an insulating layer, non-insulated magnets have a charging delay due to the existence of inter-turn resistance. In the equivalent circuit model of a non-insulated superconducting magnet, the inductor and the inter-turn resistance are in parallel. At the initial stage of charging, when the back electromotive force of the inductor is generated, the charging current is shunted to the inter-turn resistance branch, resulting in a charging delay. For large non-insulated magnets with a large inductance, the charging time will reach dozens of minutes to several hours, and at the same time, the magnet will also generate AC losses during the charging process.

[0003] Currently, the methods to improve the charging speed include intelligent non-insulated magnet design, increasing metal insulation, increasing the power of the power supply, and co-winding with multiple tapes. The intelligent non-insulated magnet utilizes the special change in resistivity of V2O3 under the action of temperature: when the temperature is lower than 175K, it behaves as an insulating material, and when the temperature rises to 175K, the resistance rapidly decreases and it behaves as a conductive property; through the change of resistance with temperature, the high-temperature superconducting magnet behaves as an insulated magnet at low temperature and as a non-insulated magnet when the temperature is higher than 175K. Adding a metal insulation layer will increase the inter-turn resistance, thereby reducing the time constant. The method of increasing the power of the power supply is limited by the fact that the power of the actual applied power supply cannot be increased infinitely. Co-winding with multiple tapes actually reduces the inductance of the magnet, thereby increasing the charging speed. These methods are only applicable to the design stage and have little effect on improving the charging speed of existing magnets and further improvement. Summary of the Invention

[0004] The purpose of the present invention is to provide a rapid charging structure and method for a superconducting non-insulated magnet, so as to solve the problem in the above background art that the existing technology cannot further improve the charging speed of existing magnets.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A rapid charging structure for a superconducting non-insulated magnet of the present invention includes a superconducting magnet and a mutual inductance coil disposed inside the superconducting magnet.

[0007] Further, the superconducting magnet is in a D shape, and the mutual inductance coil is circular and is disposed close to the straight edge of the D-shaped superconducting magnet.

[0008] Further, the access circuit of the mutual inductance coil is connected in series with the connection circuit of the superconducting magnet. A switching switch is installed on the access circuit of the mutual inductance coil. The connection or disconnection between the access circuit of the mutual inductance coil and the connection circuit of the superconducting magnet is realized through the switching operation of the switching switch.

[0009] Further, a diode and a fixed-value resistor are connected in parallel on the access circuit of the mutual inductance coil.

[0010] Further, the mutual inductance coil is a multi-turn superconducting coil with insulation, and the superconducting magnet is a hollow superconducting coil without insulation with an inner diameter large enough to accommodate the mutual inductance coil.

[0011] The present invention also provides a method for quickly charging a superconducting non-insulated magnet. By energizing the mutual inductance coil, an induced current is generated in the superconducting magnet by using the mutual inductance phenomenon, thereby improving the charging speed of the superconducting magnet.

[0012] As a further solution of the present invention: by winding the mutual inductance coil and the coil of the superconducting magnet in the opposite direction, the mutual inductance coefficient between the mutual inductance coil and the superconducting magnet is made negative, thereby canceling the induced magnetic field of the superconducting magnet, reducing the induced electromotive force of the superconducting magnet, and reducing the resistance to the current, so as to improve the charging speed of the superconducting magnet; negative mutual inductance means that the magnetic flux directions of the two coils are opposite, that is, the magnetic field generated by one coil weakens the magnetic flux of the other coil.

[0013] As a further solution of the present invention: by constructing a correlation analysis formula for the charging current, charging speed and mutual inductance coefficient of the superconducting magnet, it is convenient to substitute data for direct solution calculation; the charging current I L1 of the superconducting magnet has an analysis formula of:

[0014]

[0015]

[0016]

[0017]

[0018] Among them, A is the charging speed of the current source, t represents time, t0 is the time when the power supply current reaches the maximum value, I0 is the magnitude of the inductor current when the power supply current reaches the maximum value. The inductor current refers to the current in the equivalent inductor branch of the non-insulated magnet and can be regarded as the actual current of the magnet. The time constant τ is applied in the dynamic system and reflects the progress speed of the transient process of the dynamic system. In a first-order dynamic circuit, it represents the speed of charging or discharging of the capacitor or inductor; e is the natural constant; L1 is the inductance of the superconducting magnet, R1 is the equivalent radial inter-turn resistance of the superconducting magnet, M is the mutual inductance coefficient between the mutual inductance coil and the superconducting magnet, and Iop represents the power supply current, and Ip refers to the peak value of Iop.

[0019] As a further solution of the present invention: By increasing the number of turns of the mutual inductance coil, the mutual inductance coefficient is increased, and the charging speed of the superconducting magnet is increased.

[0020] As a further solution of the present invention: By increasing the surrounding area of the mutual inductance coil, the charging speed of the superconducting magnet is increased.

[0021] As a further solution of the present invention: Both the superconducting magnet and the mutual inductance coil are immersed in liquid nitrogen in the Dewar container.

[0022] As a further solution of the present invention: By connecting the superconducting magnet and the mutual inductance coil in series, the mutual inductance coil will not shunt the power supply current, and the charging efficiency is improved.

[0023] As a further solution of the present invention: By installing a switching switch on the access circuit of the mutual inductance coil, the current in the access circuit of the mutual inductance coil is disconnected from the connection circuit of the superconducting magnet after charging is completed, so as not to affect the subsequent work of the superconducting magnet.

[0024] As a further solution of the present invention: By installing a diode on the connection circuit of the mutual inductance coil, the conduction direction of the diode is the same as the current direction of the connection circuit, which helps to reduce the current of the mutual inductance coil, thus facilitating the switching operation of the switching switch and reducing the influence of the mutual inductance coil on the superconducting magnet when the switching switch performs the switching operation.

[0025] As a further solution of the present invention: The superconducting magnet of this application is made of V2O3 material; and the superconducting magnet is wound with multiple tapes.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: In the rapid charging method of the superconducting non-insulated magnet of the present invention, by setting up a mutual inductance coil and energizing it, an induced current is generated in the superconducting magnet by using the mutual inductance phenomenon, thereby improving the charging speed of the superconducting magnet. Its basic principle is to use the induced magnetic field of the mutual inductance coil to cancel the induced magnetic field of the superconducting magnet, thereby reducing the induced electromotive force of the superconducting magnet, reducing the resistance to the current, and ultimately achieving an increase in the charging speed. Therefore, the winding direction of the mutual inductance coil of the present application is opposite to that of the superconducting magnet coil, that is, the mutual inductance coefficient is made negative, so as to weaken the induced electromotive force of the superconducting magnet.

[0027] In order to increase the mutual inductance coefficient between the mutual inductance coil and the superconducting magnet and accelerate the charging speed of the superconducting magnet, further improvements are made in the number of coil turns, the relative position of the coils, the winding direction of the coils, etc.

[0028] Regarding the relative position of the coils, in the present application, the mutual inductance coil is arranged inside the coil of the superconducting magnet, so as to reduce the distance between the two coils, enhance the magnetic field coupling between the coil of the superconducting magnet and the mutual inductance coil, and increase the mutual inductance coefficient. Regarding the winding direction of the coils, the winding direction of the mutual inductance coil of the present application is opposite to that of the superconducting magnet coil, that is, the mutual inductance coefficient is made negative, so as to weaken the induced electromotive force of the superconducting magnet and accelerate the charging speed of the superconducting magnet. Further, through multiple groups of tests, the influence of the number of coil turns and the inner diameter of the coil on the effect of the rapid charging method of the present invention is clarified for practical application.

[0029] The circuit structure provided by the present invention connects the circuits where the superconducting magnet and the mutual inductance coil are located in series, so that the mutual inductance coil will not shunt the power supply current, improving the charging efficiency. At the same time, the series connection makes the superconducting magnet and the mutual inductance coil share a power supply, reducing the equipment requirements. The unidirectional conduction performance of the diode is used to block the mutual inductance current, thereby reducing the current of the mutual inductance coil, which is beneficial to the switching operation of the switching switch and reduces the influence of the mutual inductance coil on the superconducting magnet. Description of the Drawings

[0030] Figure 1 It is a schematic diagram of the position layout of the superconducting magnet and the mutual inductance coil of the present invention;

[0031] Figure 2 It is an equivalent circuit diagram of the circuit structure of the present invention;

[0032] Figure 3 It is a schematic diagram of the change in the working state of the equivalent circuit of the present invention;

[0033] Figure 4 It is a graph showing the influence of the number of turns of the superconducting magnet of the present invention on the mutual inductance coefficient and the charging time;

[0034] Figure 5Graph showing the influence of the number of turns of the mutual inductance coil of the present invention on the charging time;

[0035] Figure 6 Graph showing the influence of the inner diameter of the mutual inductance coil of the present invention on the charging time;

[0036] Figure 7 Schematic diagram of the circuit device layout of the present invention.

[0037] In the figure: 1. Superconducting magnet; 2. Mutual inductance coil. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] Please refer to Figure 1 , Figure 1 is a schematic diagram of the layout of the superconducting magnet 1 and the mutual inductance coil 2 for the rapid charging method of the superconducting magnet 1 in the embodiments of the present application. The principle structure of the rapid charging method of the superconducting non-insulated magnet includes a superconducting magnet 1 and a mutual inductance coil 2, wherein the mutual inductance coil 2 is insulated, the mutual inductance coil 2 is a multi-turn circular superconducting magnet 1 coil with insulation closely wound, and the superconducting magnet 1 is a hollow non-insulated superconducting magnet 1 coil with an inner diameter large enough to accommodate the mutual inductance coil 2. Referring to the existing mature technology that can improve the charging speed of the superconducting magnet 1, the following settings are made in the present application:

[0040] The superconducting magnet 1 of the present application uses multi-tape co-winding to improve the current density: superconducting materials have the ability to maintain the superconducting state at high current densities. By adopting the multi-tape co-winding method, more superconducting materials can be integrated into the magnet structure, thereby improving the overall current-carrying capacity without increasing the volume and weight of the magnet; it helps to generate a stronger magnetic field in the superconducting magnet 1;

[0041] At the same time, multi-tape co-winding can make the magnetic field distribution of the superconducting magnet 1 more uniform. During the winding process, by precisely controlling the arrangement and winding method of each tape, the intensity and direction of the magnetic field can reach the required uniformity at different positions; the superconducting magnet 1 needs to withstand large electromagnetic forces and thermal stresses during operation. By adopting the multi-tape co-winding method, the structure of the magnet can be made more solid and the mechanical stability can be improved. At the same time, the interaction between multi-tapes also helps to disperse and balance the stress, reducing the risk of damage to the magnet due to uneven stress.

[0042] When the superconducting magnet 1 operates in the superconducting state, its resistance is zero, so there is no Joule heat loss. By using the method of co-winding multiple tapes, the efficiency of the magnet can be further improved while maintaining the superconducting state, the energy consumption can be reduced, and it is convenient for the superconducting magnet 1 to operate stably for a long time. By adopting the method of co-winding multiple tapes, the winding method and arrangement method of the magnet can be flexibly designed, so as to generate a superconducting magnet 1 with a complex magnetic field configuration.

[0043] The rapid charging method of the superconducting non-insulated magnet of the present invention places the mutual inductance coil 2 inside the superconducting magnet 1 and energizes it, and uses the mutual inductance phenomenon to generate an induced current in the superconducting magnet 1, thereby increasing the charging speed of the superconducting magnet 1; the mutual inductance coefficient between the mutual inductance coil 2 and the superconducting magnet 1 is negative, and negative mutual inductance means that the magnetic flux directions of the two coils are opposite, that is, the magnetic field generated by one coil weakens the magnetic field of the other coil.

[0044] The present invention does not limit the shape and size of the superconducting magnet 1 and the mutual inductance coil 2. Figure 1 The structure shown is only for illustrative purposes of the embodiment.

[0045] The working process of the rapid charging method of the present application is described below:

[0046] Please refer to Figure 2 and Figure 3 , Figure 2 is the equivalent circuit of the circuit structure for implementing the rapid charging method of the superconducting non-insulated magnet of the present application; Figure 3 It includes the overall circuit (a), the circuit state diagram at the start of charging (b), and the circuit state diagram at the end of charging (c). The power supply supplies power to the mutual inductance coil 2 and the superconducting magnet 1. In the diagram, L1 is the inductance of the superconducting magnet 1, and R1 is the equivalent radial inter-turn resistance of the superconducting magnet 1, that is, the resistance of the current path composed of the metal layer and the gap between the tapes wound around the superconducting magnet 1. When the current in the superconducting magnet 1 is stable, the current does not flow through the inter-turns, and when the current changes, there will be current flowing through the inter-turns; L2 is the inductance of the mutual inductance coil 2.

[0047] After the circuit structure is connected, it is in the form described in the overall circuit (a), including two parts. One part is the connected circuit where the superconducting magnet 1 is located, which is equivalent to the radial resistance R1 and the inductance L1; the other part is the access circuit where the mutual inductance coil 2 is located, and a fixed-value resistor R2 and a diode are provided thereon; the fixed-value resistor R2 cooperating with the diode is added to release the energy on the mutual inductance coil 2, which helps to reduce the current on the mutual inductance coil 2, thereby facilitating the switching of the switch from position one (i.e., Figure 2 the position of ① in Figure 2At the position of ②, the circuit where the mutual inductance coil 2 is located is disconnected. After the superconducting magnet 1 is charged, the change-over switch S is switched to position two. During the process of the mutual inductance coil releasing energy through the fixed-value resistor R2, the influence of the mutual inductance coil 2 on the superconducting magnet 1 is reduced.

[0048] At this time, the superconducting magnet 1 is connected to the power supply device through the circuit. By the opening and closing of the power supply device itself and the change of the output current magnitude, the working state of the superconducting magnet 1 and the circuit where it is located is controlled; one end of the circuit where the mutual inductance coil 2 is located is connected to the power supply device, and the other end is connected to position one of the change-over switch. At this time, the change-over switch is located at position one, making the circuit where the mutual inductance coil 2 is located connected to the power supply device.

[0049] After the circuit of the mutual inductance coil 2 is connected, the charging process begins. First, the impedance of the mutual inductance coil 2 itself will delay the increase of the current. Then, when the current of the mutual inductance coil 2 reaches the maximum and remains stable (the maximum current that the mutual inductance coil 2 can withstand is less than the maximum current of the superconducting magnet 1, so it can enter the stable state relatively quickly), the state of the circuit at this time is as Figure 3 shown in (b), only considering the inductance of the mutual inductance coil 2;

[0050] After the superconducting magnet 1 is charged, the change-over switch is switched from position one to position two, and the state is as Figure 3 shown in (c). At this time, the entire circuit where the mutual inductance coil 2 is located is disconnected from the circuit where the superconducting magnet 1 is located. That is, the change-over switch is set to remove the circuit where the mutual inductance coil 2 is located after charging, so as not to affect the subsequent work of the non-insulated magnet.

[0051] According to circuit theory and the Laplace transform law, the analytical formula for the charging current of the superconducting magnet 1 in Figure 3 is derived as follows:

[0052] Based on circuit theory and the Laplace transform law, Figure 3 the complex frequency domain analytical formula for the coil charging current of the non-insulated superconducting magnet 1 in (b) is:

[0053]

[0054]

[0055] The solution of the above complex frequency domain equation is:

[0056]

[0057]

[0058] Through the inverse Laplace transform:

[0059]

[0060]

[0061] The charging speed is:

[0062]

[0063] After the current source obtains the peak value Ip, Figure 3 The complex frequency domain analytical formula of the charging current in (b) is:

[0064]

[0065]

[0066]

[0067] Through the inverse Laplace transform:

[0068]

[0069]

[0070] The charging speed is:

[0071]

[0072] To sum up, according to the circuit theory and the Laplace transform law, Figure 3 The analytical formula of the charging current of the superconducting magnet 1 in

[0073]

[0074]

[0075]

[0076]

[0077] Among them, A is the charging speed of the current source, t represents time, t0 is the time when the power supply current reaches the maximum value, I0 is the magnitude of the inductor current when the power supply current reaches the maximum value. The inductor current refers to the current in the equivalent inductor branch of the non-insulated magnet and can be regarded as the actual current of the magnet. The time constant τ is applied in the dynamic system and reflects the progress speed of the dynamic system's transient process. In a first-order dynamic circuit, it represents the speed of charging or discharging of the capacitor or inductor; e is the natural constant; s represents the complex frequency, which is used to describe the frequency characteristics in the circuit; L1 is the inductance of superconducting magnet 1, R1 is the equivalent radial inter-turn resistance of superconducting magnet 1, M is the mutual inductance coefficient between the mutual inductance coil 2 and superconducting magnet 1, and Iop represents the power supply current, and Ip refers to the peak value of Iop; by constructing the correlation analysis formula of the charging current, charging speed, and mutual inductance coefficient of superconducting magnet 1, it is convenient to substitute data for solution calculation, and obtain tables and data graphs;

[0078] On the premise that the power of the power supply and the materials and designs of superconducting magnet 1 itself have been determined, the charging speed of superconducting magnet 1 can be affected by the magnitude of the mutual inductance coefficient between superconducting magnet 1 and mutual inductance coil 2;

[0079] Common factors that can affect the magnitude of the mutual inductance coefficient between superconducting magnet 1 and mutual inductance coil 2 include: the number of turns of the coil, the relative position of the coils, the winding direction of the coils, the geometric shape and size of the coils, etc.;

[0080] Regarding the relative position of the coils, please refer to Figure 1-2 , in this application, the mutual inductance coil 2 is arranged inside the coil of superconducting magnet 1 to reduce the distance between the two coils, enhance the magnetic field coupling between the coil of superconducting magnet 1 and the mutual inductance coil 2, and increase the mutual inductance coefficient; regarding the winding direction of the coils, the basic principle of this application is to use the induced magnetic field of the mutual inductance coil 2 to cancel the induced magnetic field of superconducting magnet 1, thereby reducing the induced electromotive force of superconducting magnet 1, reducing the resistance to the current, and finally achieving an increase in the charging speed. Therefore, the winding direction of the mutual inductance coil 2 and the coil of superconducting magnet 1 in this application is opposite, that is, the mutual inductance coefficient M is negative, so as to weaken the induced electromotive force of superconducting magnet 1;

[0081] For the coil geometry, the coils of the superconducting magnet 1 in this embodiment are D-shaped, and the mutual inductance coil 2 is circular and is arranged inside the coils of the superconducting magnet 1 near the straight side. The magnetic field distribution of the D-shaped coil has a certain directionality. When current passes through the D-shaped coil, the magnetic field is mainly concentrated near the straight side, forming a relatively strong magnetic field region. By arranging the mutual inductance coil 2 in the region near the straight side, a stronger mutual inductance coefficient can be obtained; in this embodiment, the coils of the superconducting magnet 1 are divided into a straight side and a circular side. The radius of the circular side is called the large circle radius and is denoted by r1; the transition section between the straight side and the circular side is set as a quarter-circle arc, and the radius of this arc is called the small circle radius and is denoted by r2; then the actual length of the straight side should be twice r1 minus the radii r2 of the two arcs, that is, 2(r1 - r2).

[0082] Therefore, in this embodiment, the effects of the charging method of this application are mainly illustrated by changing the number of turns of the coils of the superconducting magnet 1 and the mutual inductance coil 2, as well as the inner diameter size of the mutual inductance coil 2. The specific embodiments, experimental data and analysis are as follows:

[0083] In this embodiment, the original structural parameters of the superconducting magnet 1 and the mutual inductance coil 2 are shown in Table 1.

[0084] Table 1 Main structural parameters of the superconducting magnet 1 and the mutual inductance coil 2

[0085]

[0086] Construct a circuit from the structural parameters in Table 1. Under the condition that the charging speed of the current source is 2 A / s, the charging processes of the 4-turn coils of the superconducting magnet 1 and the 20-turn coils of the superconducting magnet 1 are as Figure 3 shown; the specific parameters are shown in Table 2:

[0087] Table 2 Influence of the number of turns of the coils of the superconducting magnet 1 on the mutual inductance coefficient and the charging time

[0088]

[0089] In Table 2 above, the input current speed is 2 A per second, and the mutual inductance coefficient of 0 means that the mutual inductance coil 2 is not connected;

[0090] It can be seen from the comparison of the first row and the third row in Table 2: when the mutual inductance coil 2 is not connected, when the number of turns of the coils of the superconducting magnet 1 changes from 4 turns to 20 turns, the charging time increases from 355 seconds to 464 seconds; that is, the increase in the inductance caused by the increase in the number of turns of the coils of the superconducting magnet 1 itself will lead to an extension of the charging time;

[0091] It can be seen from the comparison between the second row and the fourth row in Table 2 that: when the superconducting magnet 1 is in the state of accessing the mutual inductance coil 2 and the number of turns of the superconducting magnet 1 coil changes from 4 turns to 20 turns, it will lead to an increase in the mutual inductance coefficient, and at the same time, the charging time extends from 336 seconds to 455 seconds;

[0092] It can be seen from the comparison between the first row and the second row in Table 2 that: when the number of turns of the superconducting magnet 1 coil is 4 turns, after accessing the mutual inductance coil 2, the charging time decreases from 355 seconds to 336 seconds, and the charging time accelerated by the mutual inductance coil is 9 seconds;

[0093] It can be seen from the comparison between the third row and the fourth row in Table 2 that: when the number of turns of the superconducting magnet 1 coil is 20 turns, after accessing the mutual inductance coil 2, the charging time decreases from 464 seconds to 455 seconds, and the charging time accelerated by the mutual inductance coil is 19 seconds;

[0094] In summary, from Figure 4 and combining the data in Table 2, the conclusion can be drawn that: the more the number of turns of the superconducting magnet 1 coil, the stronger the self-inductance L1 value of itself, which prolongs the charging time; while accessing the mutual inductance coil 2 can reduce the charging time. The more the number of turns of the superconducting magnet 1 coil, the greater the mutual inductance coefficient M will be, but compared with L1, the change in the mutual inductance coefficient is very small, resulting in a decrease in M / L1, thus reducing the acceleration effect.

[0095] Construct a circuit from the structural parameters in Table 1 (changing the number of turns of the mutual inductance coil 2). Under the condition of a charging speed of 2 A / s of the current source and a 4-turn superconducting magnet 1 coil, the accelerating charging effect of the mutual inductance coil 2 with different numbers of turns on the 4-turn superconducting magnet 1 is as Figure 3 shown in (b); the specific parameters are shown in Table 3:

[0096] Table 3 Influence of the number of turns of the mutual inductance coil on the charging time

[0097]

[0098] In the test, the maximum current of the superconducting magnet 1 is set to 200 A. When the input current speed is 2 A / s, Figures 4-6 the horizontal section after the maximum current in Figure 5 reaches 200 A represents the stage after the mutual inductance between the mutual inductance coil 2 and the superconducting magnet 1 completely compensates or even over-compensates the inductance of the superconducting magnet 1. It can be seen from Table 3 that under the condition of a charging speed of 2 A / s of the current source and a 4-turn superconducting magnet 1, as the number of turns of the mutual inductance coil 2 gradually increases, the charging time of the superconducting magnet 1 gradually decreases. When the number of turns of the mutual inductance coil 2 is 90, the charging time is 97 seconds, which is less than the charging time of the superconducting magnet 1 in the ideal state without accessing the mutual inductance coil 2. In summary, from Figure 5 and combining the data in Table 3, the conclusion can be drawn that: increasing the number of turns of the mutual inductance coil 2 can reduce the charging time of the superconducting magnet 1; increasing the number of turns of the mutual inductance coil 2 can increase the mutual inductance coefficient between the mutual inductance coil 2 and increase the charging speed of the superconducting magnet 1.

[0099] Construct a circuit from the structural parameters in Table 1 (the inner diameter of the mutual inductance coil 2 is changed). Under the condition that the charging speed of the current source is 2 A / s and there are 4 turns of coils, the accelerating charging effect of the mutual inductance coil 2 with different inner diameters on the 4-turn superconducting magnet 1 is as Figure 3 shown in (c); the specific parameters are shown in Table 4:

[0100] Table 4 Influence of the inner diameter of the mutual inductance coil on the charging time

[0101]

[0102] From Figure 6 Combined with Table 4, it can be seen that as the inner diameter of the mutual inductance coil 2 increases, the charging time decreases with the increase of the inner diameter of the mutual inductance coil 2. When the inner diameter of the mutual inductance coil 2 reaches 0.2 m (the mutual inductance coil 2 of the present application is arranged inside the superconducting magnet 1, and the inner diameter of the coil of the superconducting magnet 1 adopted in the present application is 0.233 m, so the mutual inductance coil 2 with an inner diameter of 0.2 m is basically at the maximum). The charging time is less than 100 seconds, that is, the charging speed exceeds the charging speed of the current source. That is, increasing the inner diameter of the mutual inductance coil 2 and thus increasing the surrounding area of the mutual inductance coil 2 can increase the mutual inductance coefficient between the mutual inductance coil 2 and the superconducting magnet 1, and thus reduce the charging time of the superconducting magnet 1. In summary, from Figure 3 The conclusion drawn from (c) combined with the data in Table 4 is: increasing the inner diameter of the mutual inductance coil 2 can reduce the charging time of the superconducting magnet 1.

[0103] The present invention also provides a charging structure for implementing the above fast charging method; it includes:

[0104] A superconducting magnet 1, including a D-shaped or circular hollow non-insulated superconducting coil with an inner diameter large enough to accommodate the mutual inductance coil 2;

[0105] A mutual inductance coil 2, including a closely wound multi-turn circular insulated superconducting coil;

[0106] Electrical wiring, connecting the superconducting non-insulated coil and the mutual inductance coil 2 in series, and a switching device for controlling the access of the mutual inductance coil 2; by connecting the superconducting magnet 1 and the mutual inductance coil 2 in series, the mutual inductance coil 2 will not shunt the power supply current, improving the charging efficiency; at the same time, the series connection makes the superconducting magnet 1 and the mutual inductance coil 2 share a power supply, reducing the equipment requirements.

[0107] A switching switch is installed on the access circuit of the mutual inductance coil 2. Through the switching operation of the switching switch, the access circuit of the mutual inductance coil 2 is connected or disconnected from the circuit where the superconducting magnet 1 is located. After charging is completed, the connected current between the access circuit of the mutual inductance coil 2 and the superconducting magnet 1 is disconnected, so as not to affect the subsequent operation of the superconducting magnet 1.

[0108] When an electric current passes through an inductor (i.e., a coil), a magnetic field is generated around it. This magnetic field is related to the magnitude and direction of the current. According to Faraday's law of electromagnetic induction, when the magnetic flux through a closed circuit changes, an induced electromotive force (emf) is generated in the circuit. In an inductor, when the current changes, the magnetic field around it also changes, thereby generating an induced emf in the coil. The direction of this induced emf is opposite to the direction of the current change, so it will impede the change of the current. Therefore, when the switching switch disconnects the mutual inductance coil 2 from the circuit, the induced emf of the mutual inductance coil 2 excites an induced current in the opposite direction to the input current. To avoid the influence of this induced current on the charging operation of the superconducting magnet 1, a diode is installed in the circuit between the mutual inductance coil 2 and the switching switch. The conduction direction of the diode is consistent with the current direction, and the unidirectional conduction performance of the diode is used to block the mutual inductance current, thereby reducing the current of the mutual inductance coil 2 during the switching process of the switching switch, which is beneficial to the switching operation of the switching switch and reduces the influence of the mutual inductance coil 2 on the superconducting magnet 1.

[0109] Furthermore, it also includes a Dewar vessel and a power supply device for maintaining the operation of the circuit structure. Please refer to Figure 7 , the Dewar vessel is used to contain liquid nitrogen, and the superconducting magnet 1 and the mutual inductance coil 2 are immersed in the liquid nitrogen; the power supply device is used to supply power to the superconducting magnet 1 and can provide a ramp current at a stable rate.

[0110] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content without departing from the technical solution scope of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A superconducting non-insulated magnet fast charging structure, characterized in that: The invention comprises a superconducting magnet (1) and a mutual inductance coil (2) arranged inside the superconducting magnet (1); an access circuit of the mutual inductance coil (2) is connected in series with a connection circuit of the superconducting magnet (1); a switching switch is installed on the access circuit of the mutual inductance coil (2); and the connection or disconnection between the access circuit of the mutual inductance coil (2) and the connection circuit of the superconducting magnet (1) is achieved through the switching operation of the switching switch.

2. A superconducting non-insulated magnet fast charging structure according to claim 1, characterized in that: The superconducting magnet (1) is arranged in a D-shape, and the mutual inductance coil (2) is circular and arranged close to a straight edge of the D-shaped superconducting magnet (1).

3. A superconducting non-insulated magnet fast charging structure according to claim 1, characterized in that: A diode and a fixed value resistor are connected in parallel to the access circuit of the mutual inductance coil (2).

4. A superconducting non-insulated magnet fast charging structure according to claim 1, characterized in that: The mutual induction coil (2) is a multi-turn superconducting coil with insulation, and the superconducting magnet (1) is a hollow non-insulated superconducting coil with an inner diameter sufficient to accommodate the mutual induction coil (2).

5. A charging method for a superconducting non-insulated magnet fast charging structure according to any one of claims 1 to 4, characterized in that: By energizing the mutual induction coil (2), an induced current is generated in the superconducting magnet (1) by utilizing the mutual induction phenomenon, so as to increase the charging speed of the superconducting magnet (1).

6. A charging method for a superconducting non-insulated magnet fast charging structure according to claim 5, characterized in that: By winding the mutual inductance coil (2) and the coil of the superconducting magnet (1) in opposite directions, the mutual inductance coefficient between the mutual inductance coil (2) and the superconducting magnet (1) is made negative, thereby offsetting the induced magnetic field of the superconducting magnet (1), reducing the induced electromotive force of the superconducting magnet (1), and reducing the resistance to the current, so as to increase the charging speed of the superconducting magnet (1).

7. The charging method of a superconducting non-insulated magnet fast charging structure according to claim 5, characterized in that: By increasing the number of turns of the mutual inductance coil (2), the mutual inductance coefficient is increased, thereby increasing the charging speed of the superconducting magnet (1); And / or, by increasing the surrounding area of ​​the mutual inductance coil (2), the charging speed of the superconducting magnet (1) is increased.

8. The charging method of a superconducting non-insulated magnet fast charging structure according to claim 5, characterized in that: By connecting the superconducting magnet (1) and the mutual inductance coil (2) in series, the mutual inductance coil (2) will not shunt the power supply current, thereby improving the charging efficiency.

9. The charging method of a superconducting non-insulated magnet fast charging structure according to claim 5, characterized in that: By installing a switching switch on the access circuit of the mutual inductance coil (2), the current of the access circuit of the mutual inductance coil (2) and the connection circuit of the superconducting magnet (1) is disconnected after charging is completed, thereby not affecting the subsequent operation of the superconducting magnet (1).

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