A superconducting magnet excitation device based on full-wave transformer rectifier

Abstract

The present application discloses a superconducting magnet excitation device based on a full-wave transformer rectifier, comprising a power supply, a transformer, and two superconducting switches. The transformer comprises a winding support, a primary winding, and two secondary windings. The primary winding is wound on the outer wall of the winding support, and its two ends are connected to the positive and negative poles of the power supply; the two secondary windings are coaxially wound on the primary winding, and the secondary windings are composed of multiple superconducting wires. The superconducting wires in each secondary winding are insulated from each other and arranged in parallel; the two superconducting switches are correspondingly arranged next to the two secondary windings, and the parallel points of the multiple superconducting wires in each secondary winding are respectively connected to the two ends of the superconducting magnet. The present application can effectively increase the output current of the superconducting magnet excitation device and meet the high output current requirements of superconducting loads.

Description

Technical Field

[0001] The present application belongs to the field of superconducting electrical technology, and more specifically, relates to a superconducting magnet excitation device based on a full-wave transformer rectifier. Background Art

[0002] With the development of new superconducting materials and superconducting wire manufacturing technologies, the research and development, preparation and application of superconducting materials have entered the stage of widespread commercialization. Superconducting magnets made of various types of superconducting wires are being increasingly used in various high-parameter and strong magnetic field fields, such as nuclear magnetic resonance and magnetic resonance imaging (NMR and MRI), steady-state high-field strength magnets, superconducting motors, superconducting magnetic levitation technology, controlled nuclear fusion, etc.

[0003] In the power supply and excitation method for superconducting magnets, the superconducting magnets, operating in a cryogenic environment, are connected to a power electronic power supply operating at room temperature via current leads. However, in this power electronic power supply method, the output current is limited by the power supply's power supply capacity, making it difficult to meet the high output current requirements of some superconducting loads in some applications (such as controlled nuclear fusion). Summary of the Invention

[0004] In response to the defects of the existing technology, the purpose of this application is to provide a superconducting magnet excitation device based on a full-wave transformer rectifier, aiming to solve the problem that the traditional power supply and excitation method of superconducting magnets cannot meet the requirements of some superconducting loads for large output current.

[0005] To achieve the above objectives, the present application provides a superconducting magnet excitation device based on a full-wave transformer rectifier, comprising a power supply, a transformer, and two superconducting switches. The transformer comprises a winding support, a primary winding, and two secondary windings. The primary winding is wound on the outer wall of the winding support, and the two ends of the primary winding are connected to the positive and negative poles of the power supply respectively.

[0006] Two secondary windings are coaxially wound on the primary winding. The secondary windings are composed of multiple superconducting wires. The superconducting wires in each secondary winding are insulated from each other and arranged in parallel. Two superconducting switches are correspondingly arranged next to the two secondary windings, and the parallel points of the multiple superconducting wires in each secondary winding are respectively connected to the two ends of the superconducting magnet.

[0007] The present application provides a superconducting magnet excitation device based on a full-wave transformer rectifier. The two secondary windings in the transformer use multiple superconducting wires, and the multiple superconducting wires in each secondary winding form a parallel structure, which can effectively increase the output current of the excitation device; and the primary winding is wound on the outer wall of the winding support, and the two secondary windings are coaxially wound on the primary winding, which can further improve the compactness of the device.

[0008] As a further preference, the superconducting wires in the two secondary windings adopt a spiral structure, and the superconducting wires in the two secondary windings are staggered and coaxially wound on the primary winding.

[0009] As a further preference, the superconducting wires in the two secondary windings adopt a ring structure.

[0010] As a further preference, the two secondary windings are two half turns of the same superconducting wire loop separated by two output connecting leads as dividing points.

[0011] As a further preferred embodiment, when an alternating current is passed through the primary winding of the transformer and the two superconducting switches are controlled to be turned on and off according to a certain time sequence, the function of rectifying and charging the superconducting magnet can be achieved.

[0012] As a further preference, the alternating current is a superposition of one or more of a triangular wave, a trapezoidal wave and a sine wave.

[0013] As a further preferred embodiment, a ramp current is passed through the primary winding of the transformer, and one of the superconducting switches is controlled to be always in the on state, and the other superconducting switch is controlled to be always in the off state, so as to realize the multiplexing function of the DC transformer.

[0014] As a further preference, the superconducting switch adopts an alternating magnetic field switch or a pulse switch.

[0015] As a further preference, the pulse switch is a thermal pulse switch or a magnetic field pulse switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is an equivalent circuit diagram of a superconducting magnet excitation device based on a full-wave transformer rectifier provided by the present application;

[0017] Figure 2 This is an equivalent circuit diagram of the superconducting magnet excitation device based on the full-wave transformer rectifier provided by the present application when the DC transformer multiplexes the function;

[0018] Figure 3 Schematic diagram of a superconducting magnet excitation device based on a full-wave transformer rectifier provided by the present application, which adopts a planar double-winding structure;

[0019] Figure 4 This is a schematic diagram of a superconducting magnet excitation device based on a full-wave transformer rectifier provided by the present application, which adopts a pulse switch parallel multi-winding structure;

[0020] Figure 5 This is a schematic diagram of a superconducting magnet excitation device based on a full-wave transformer rectifier provided by the present application, which adopts a magnetic field switch parallel multi-winding structure;

[0021] Figure 6A This is a schematic diagram of a superconducting magnet excitation device based on a full-wave transformer rectifier provided in an embodiment of the present application, which uses a planar double-winding structure to charge a superconducting coil load wound with a 10 mm wide ReBCO high-temperature superconducting tape;

[0022] Figure 6B yes Figure 6A Provides an intuitive equivalent circuit diagram of each component in the superconducting magnet excitation device based on a full-wave transformer rectifier;

[0023] Figure 7 This is a schematic diagram of a superconducting magnet excitation device based on a full-wave transformer rectifier provided in an embodiment of the present application, which uses a thermal pulse switching parallel multi-winding structure to charge a double-helix superconducting coil load wound by a CORC superconducting cable;

[0024] Figure 8 This is a schematic diagram of a superconducting magnet excitation device based on a full-wave transformer rectifier provided in an embodiment of the present application, which uses an alternating magnetic field switch parallel multi-winding structure to charge a superconducting coil load wound with a 10 mm wide ReBCO high-temperature superconducting tape;

[0025] Figure 9 This is a schematic diagram of a superconducting magnet excitation device based on a full-wave transformer rectifier provided in an embodiment of the present application using a pulsed magnetic field switch parallel multi-winding structure to charge a double-helix superconducting coil load wound by a CORC superconducting cable.

[0026] In all the drawings, the same reference numerals are used to represent the same elements or structures, where: 1 is a primary winding, 2 and 3 are two secondary windings, 4 is a superconducting switch control element, 5 is a superconducting load, 6 is an output connecting lead, 7 is a superconducting load skeleton and its supporting structure, and 8 is a connecting terminal between the output connecting lead and the superconducting load. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0028] It should be understood that, in the description of this application, the term "several" means at least one, such as one, two, etc., unless otherwise clearly and specifically defined; the term "plurality" means two or more, unless otherwise clearly and specifically defined; the terms "first" and "second" etc. are used to distinguish different objects, rather than to describe a specific order of objects; the term "and / or" includes any and all combinations of one or more related listed items.

[0029] Additionally, references throughout this specification to "one embodiment," "one embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Thus, appearances of the phrase "in one embodiment," "in one embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0030] The superconducting magnet excitation device of the full-wave transformer rectifier provided in this application mainly includes a transformer, a superconducting switch and a power supply. The transformer includes a primary winding and two secondary windings. Among them, the primary winding of the transformer is a superconducting material or a normal conductive material, and the secondary winding of the transformer is a superconducting material. Its equivalent circuit is as follows Figure 1 As shown: Where L1 represents the primary winding of the transformer; L 2a and L 2b Respectively represent the two secondary windings of the transformer; S a and S b represents two superconducting switches; L represents the superconducting load; i1 represents the primary side current of the transformer, i 2a Indicates the transformer secondary winding L 2a The current, i 2b Indicates the transformer secondary winding L 2b The current; i L Represents the load current. Superconducting switch S a and S b It is opened and closed by means of magnetic control or thermal control. There is no resistance in the on state and resistance in the off state. When an alternating current i1 with a specific waveform (such as a symmetrical or asymmetrical triangle wave, trapezoidal wave, sine wave with any optional duty cycle, or a superposition of the above waveforms) is passed through the primary side of the transformer, the superconducting switch S a and S b The conduction and disconnection at a certain time sequence can achieve the effect of rectifying and charging the load L.

[0031] Furthermore, the topology proposed in this application also includes a DC transformer multiplexing function, which is implemented as follows: the power supply provides a ramp current to the primary winding. When the superconducting switch on one side is always in the on state and the superconducting switch on the other side is always in the off state, the equivalent circuit diagram is as follows: Figure 2 As shown, where R b is the superconducting switch S b The resistor is in the disconnected state. A current i1 rising from zero to a constant value is passed through the primary side of the transformer. When the primary side current rises, the secondary side L 2a and L 2b The branches sense the current that gradually increases from zero. When the primary current enters a constant state, L 2aThe branch has no other resistance except the small welding resistance, and the current is basically not attenuated. 2b Since the switch is in the off state, there is a resistor R with a large resistance value. b , the current in this branch rapidly decays to zero after the primary current of the transformer stops changing, and the final load current i L Equal to i 2a , forming a certain ratio with the primary-side current i1, thus realizing the reuse function of the DC transformer. Compared with the traditional current-lead power supply method, the DC transformer has the advantage of lower output current requirements for the power electronic power supply. Through the transformer's current-boosting effect, a small current on the primary side can generate a larger current on the secondary side. Compared with the transformer-rectifier flux pump power supply method, it has the advantage of not requiring complex switch timing control and has a simpler control method.

[0032] Based on the above equivalent circuit and working principle, in order to increase the output current of the superconducting excitation device, the present application has made the following improvements to the device:

[0033] The primary winding of the transformer is wound on the outer wall of a winding support (such as a frame or an iron core), and can be specifically spirally wound or layer wound. The two ends of the primary winding of the transformer are connected to the positive and negative poles of the power supply respectively.

[0034] Two secondary windings are coaxially wound around the primary winding. Each secondary winding is constructed using n (n ≥ 2) superconducting wires. The superconducting wires in each secondary winding are insulated from each other and arranged in parallel. This embodiment employs n parallel superconducting wires for the secondary winding. Compared to using a single superconducting wire, connecting multiple superconducting wires in parallel increases the total output current by n times, effectively increasing the output current.

[0035] The two superconducting switches are correspondingly arranged beside the two secondary windings. The two superconducting switches can adopt pulse switches, such as thermal pulse switches or magnetic field pulse switches, or alternating magnetic field switches, which is not limited in this embodiment.

[0036] The parallel points of multiple superconducting wires in each secondary winding are respectively connected to the two ends of the superconducting magnet. During operation, a current with a specific waveform is passed through the power supply to the primary winding, and the superconducting magnet is charged by controlling the conduction and disconnection of the two superconducting switches.

[0037] Specifically, the superconducting magnet excitation device provided in the present application can adopt a planar double-winding structure, a pulse switch parallel multi-winding structure and a magnetic field switch parallel multi-winding structure, respectively. Figure 3 、 Figure 4 and Figure 5 As shown. Figure 3As shown, the superconducting wires in the two secondary windings provided by the present application can both adopt a spiral structure, and the superconducting wires in the two secondary windings are staggered and coaxially wound on the primary winding. Figure 4 and Figure 5 As shown, the superconducting wires in the two secondary windings provided by the present application may adopt a ring structure.

[0038] When the two secondary windings have the same number of turns, the two secondary windings can be two half turns of the same superconducting wire loop separated by two output connecting leads, and multiple superconducting wire loops are coaxially arranged on the primary winding.

[0039] The present application provides a superconducting magnet excitation device based on a full-wave transformer rectifier. The two secondary windings in the transformer use multiple superconducting wires, and the multiple superconducting wires in each secondary winding form a parallel structure, which can effectively increase the output current of the excitation device; and the primary winding is wound on the outer wall of the winding support, and the two secondary windings are coaxially wound on the primary winding, which can further improve the compactness of the device.

[0040] The superconducting magnet excitation device provided by the present application is described below with reference to specific embodiments.

[0041] FIG6 shows an embodiment of the present application. Figure 6A The structure shown is a planar dual-winding structure proposed in this application, in which a superconducting coil load wound with a 10 mm wide ReBCO high-temperature superconducting tape is charged. Reference numeral 1 represents the primary winding of the transformer, which is wound with a copper wire; reference numerals 2 and 3 represent one of the two windings on the secondary side of the transformer, each wound with a superconducting material. The two ends of the same winding are welded to the upper end of the superconducting switch tape on one side and the lower end of the superconducting switch tape on the other side, respectively. Reference numeral 2 represents the secondary winding of the transformer and the superconducting switch on the left side of the image, forming one half-bridge of a full-wave rectifier circuit. Reference numeral 3 represents the secondary winding of the transformer, which is shaded in the figure, and forms the other half-bridge of the full-wave rectifier circuit with the superconducting switch on the right side of the image.

[0042] Figure 6B is an intuitive equivalent circuit diagram of each component of the structure, where Figure 6A The secondary winding represented by 2 is Figure 6B L2a corresponds to, Figure 6A The secondary winding represented by 3 is Figure 6BL2b corresponds to the following: 4 represents the control electromagnet of the magnetically controlled superconducting switch, which controls the quenching of the superconducting switch strip by triggering the electromagnets in a certain sequence to act on the superconducting switch strip placed in the iron core atmosphere, thereby controlling the on and off of the magnetically controlled superconducting switch, and then realizing the rectification of the input waveform of the primary winding of the transformer and the charging of the superconducting load; 5 represents the charged superconducting coil load; 6 represents the output connection lead; 7 represents the skeleton of the superconducting coil load and its supporting structure. Figure 6A In the structure shown, multiple components including the transformer primary copper winding, two transformer secondary superconducting windings, and two magnetically controlled superconducting switches are arranged closely, and the transformer primary winding and secondary winding are placed coaxially, which improves the compactness of the structure; each secondary winding is composed of multiple superconducting tapes, and the above-mentioned multiple superconducting tapes form a parallel structure, which effectively increases the output current of the flux pump device; the superconducting switch electromagnet is longer and has a larger air gap area, so that the superconducting switch electromagnet has a larger effective area and a larger off-state resistance, which is conducive to generating a higher load voltage at both ends of the load and faster charging; the transformer secondary winding is tightly coaxially wound around the primary winding, and the primary and secondary sides of the transformer are more tightly coupled, which is conducive to improving the efficiency of the excitation system; in addition, when the magnetically controlled superconducting switch on one side of the device structure is always on and the superconducting switch on the other side is always off, the device can be reused as a superconducting DC transformer.

[0043] Figure 7 Another embodiment of the present application is presented. Figure 7 The structure shown is a method of charging a double-helix superconducting coil load wound with a CORC superconducting cable through the thermal pulse switch parallel multi-winding structure proposed in this application. 1 represents the primary winding of the transformer, which is wound with a 2mm superconducting tape; 2 and 3 represent one of the two windings on the secondary side of the transformer, which are actually two half turns of the same 10mm superconducting tape ring separated by two output connection lead dividing lines. The secondary winding shown in the figure is composed of multiple superconducting tape rings as described above. These superconducting tape rings are welded together through the above-mentioned output connection leads, and the rest of the positions are insulated from each other, forming a structure. In a parallel structure, it is used to increase the output current of the flux pump structure; 4 represents the heater of the thermal pulse superconducting switch, which controls the quenching of each superconducting ring by triggering the heater to generate heat in a certain sequence to increase the temperature of each superconducting ring, thereby controlling the conduction and shutdown of the thermal control superconducting switch, and then realizing the rectification of the input waveform of the primary winding of the transformer and the charging of the superconducting load; 5 represents the charged double-helix superconducting coil load; 6 represents the output connecting lead; 7 represents the skeleton of the superconducting coil load and its supporting structure; 8 represents the connection terminal between the output connecting lead and the double-helix coil port of the CORC superconducting cable. Figure 7In the structure shown, the two secondary windings in the transformer belong to the same superconducting tape ring structure, and the secondary superconducting ring of the transformer is placed coaxially with the primary winding of the transformer, enhancing the compactness of the device. At the same time, a heater is used to directly heat the secondary superconducting winding to realize the function of superconducting switch, without the need to separately lead out part of the superconducting wire as a superconducting switch, further improving the compactness of the structure. The secondary winding is composed of multiple superconducting tape rings, and the multiple superconducting tape rings form a parallel structure, which effectively increases the output current of the flux pump device.

[0044] Figure 8 Another embodiment of the present application is presented. Figure 8 The structure shown is a superconducting coil load charged by a 10mm wide ReBCO high-temperature superconducting tape through the alternating magnetic field switch parallel multi-winding structure proposed in this application. 1 represents the primary winding of the transformer, which is wound with copper wire; 2 and 3 represent one of the two windings on the secondary side of the transformer, respectively. In fact, they are the left and right half turns of the same turn of 10mm superconducting tape ring with two output connecting leads as the dividing point. The above-mentioned 10mm superconducting tape ring is made by welding two 10mm tapes end to end. The secondary winding shown in the figure is composed of multiple of the above-mentioned superconducting tape rings, which are connected by the above-mentioned The output connection leads are welded together, and the rest of the positions are insulated from each other to form a parallel structure, which is used to increase the output current of the flux pump structure; 4 represents the control electromagnet of the magnetically controlled superconducting switch, which controls the quenching of the superconducting switch strip by triggering the electromagnets in a certain sequence to act on the superconducting switch strip placed in the iron core atmosphere, thereby controlling the on and off of the magnetically controlled superconducting switch, and then realizing the rectification of the input waveform of the primary winding of the transformer and the charging of the superconducting load; 5 represents the charged double-helix superconducting coil load; 6 represents the output connection lead; 7 represents the skeleton of the superconducting coil load and its supporting structure. Figure 8 In the structure shown, the two windings on the secondary side of the transformer belong to the same superconducting tape ring structure, and the secondary superconducting ring of the transformer is placed coaxially with the primary winding of the transformer, which enhances the compactness of the device. At the same time, an electromagnet is directly used to apply a magnetic field to the secondary superconducting winding to realize the function of superconducting switching, without the need to separately lead out part of the superconducting wire as a superconducting switch, further improving the compactness of the structure. The secondary winding is composed of multiple superconducting tape rings, and the multiple superconducting tape rings form a parallel structure, which effectively increases the output current of the flux pump device. The direction of the current in the superconducting switch tape is parallel to the cross-section of the electromagnet core. That is, the structure between the superconducting switch tape and the electromagnet is non-inductive, and the current in the tape will not generate an induced electromagnetic field in the core.

[0045] Figure 9 Another embodiment of the present application is presented. Figure 9The structure shown is a pulsed magnetic field switch parallel multi-winding structure proposed in this application to charge a double-helix superconducting coil load wound by a CORC superconducting cable. 1 represents the primary winding of the transformer, which is wound with 2mm superconducting tape; 2 and 3 respectively represent one of the two windings on the secondary side of the transformer, which are actually two half turns of the same 10mm superconducting tape ring separated by two output connection lead dividing lines. The secondary winding shown in the figure is composed of multiple of the above-mentioned superconducting tape rings, which are welded together by the above-mentioned output connection leads. The rest of the positions are insulated from each other to form a parallel connection. Structure, used to increase the output current of the flux pump structure; 4 represents the controller pulse magnetic field coil of the pulsed magnetic control superconducting switch, which controls the quenching by triggering the pulsed magnetic field Bp in a certain sequence so that the magnetic field of each superconducting ring exceeds the critical magnetic field, thereby controlling the on and off of the pulsed magnetic control superconducting switch, and then realizing the rectification of the waveform and the charging of the superconducting load; 5 represents the charged double-helix superconducting coil load; 6 represents the output connecting lead; 7 represents the skeleton of the superconducting coil load and its supporting structure; 8 represents the connection terminal between the output connecting lead and the double-helix coil port of the CORC superconducting cable. Figure 9 In the structure shown, the two windings on the secondary side of the transformer belong to the same superconducting tape ring structure, and the secondary side superconducting ring of the transformer is placed coaxially with the primary side winding of the transformer, which enhances the compactness of the device. At the same time, a pulsed magnetic field coil is directly used to apply a magnetic field to the secondary side superconducting winding to realize the function of superconducting switching, without the need to separately lead out part of the superconducting wire as a superconducting switch, further improving the compactness of the structure. The secondary side winding is composed of multiple superconducting tape rings, and the multiple superconducting tape rings form a parallel structure, which effectively increases the output current of the flux pump device.

[0046] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A superconducting magnet excitation device based on a full-wave transformer rectifier, comprising a power supply, a transformer and two superconducting switches, wherein the transformer comprises a winding support, a primary winding and two secondary windings, characterized in that: The primary winding is wound on the outer wall of the winding support, and the two ends of the primary winding are connected to the positive and negative poles of the power supply respectively; Two secondary windings are coaxially wound on the primary winding. The secondary windings are composed of multiple superconducting wires. The superconducting wires in each secondary winding are insulated from each other and arranged in parallel. Two superconducting switches are correspondingly arranged next to the two secondary windings, and the parallel points of the multiple superconducting wires in each secondary winding are respectively connected to the two ends of the superconducting magnet.

2. The superconducting magnet excitation device based on a full-wave transformer rectifier according to claim 1, characterized in that: The superconducting wires in the two secondary windings adopt a spiral structure, and the superconducting wires in the two secondary windings are staggered and coaxially wound on the primary winding.

3. The superconducting magnet excitation device based on a full-wave transformer rectifier according to claim 1, characterized in that: The superconducting wires in the two secondary windings adopt a ring structure.

4. The superconducting magnet excitation device based on a full-wave transformer rectifier according to claim 1 or 3, characterized in that: The two secondary side windings are two half turns of the same turn superconducting wire ring separated by two output connecting leads as dividing points.

5. The superconducting magnet excitation device based on a full-wave transformer rectifier according to claim 1, characterized in that: When an alternating current is passed through the primary winding of the transformer and the two superconducting switches are controlled to be turned on and off according to a certain timing, the function of rectifying and charging the superconducting magnet can be realized.

6. The superconducting magnet excitation device based on a full-wave transformer rectifier according to claim 5, characterized in that: The alternating current is a superposition of one or more of a triangular wave, a trapezoidal wave and a sine wave.

7. The superconducting magnet excitation device based on a full-wave transformer rectifier according to claim 1, characterized in that: By supplying a ramp current to the primary winding of the transformer and controlling one of the superconducting switches to be always in the on state and the other superconducting switch to be always in the off state, the multiplexing function of the DC transformer can be realized.

8. The superconducting magnet excitation device based on a full-wave transformer rectifier according to claim 1, characterized in that: The superconducting switch adopts an alternating magnetic field switch or a pulse switch.

9. The superconducting magnet excitation device based on a full-wave transformer rectifier according to claim 8, characterized in that: The pulse switch adopts a thermal pulse switch or a magnetic field pulse switch.

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