CN1569511B - High temperature superconducting magnetic levitation device - Google Patents

Abstract

The invention relates to a high-temperature superconducting magnetic levitation device, which comprises a high-temperature superconducting magnet, a car body, a guide rail, a position sensor and a voltage-controlled current source, wherein the high-temperature superconducting magnet made of winding high-temperature superconducting wires is controllable , the frequency of the AC component of the control current is within the range of less than 1000 Hz, and the device is used in a short-distance urban transportation vehicle, which can make the transportation vehicle have the characteristics of low energy consumption, low noise, low vibration and high environmental protection.

Description

High temperature superconducting magnetic levitation device

technical field

The invention relates to the technical field of magnetic levitation rail transit.

Background technique

The purpose of the present invention "a high-temperature superconducting magnetic levitation device" is to provide a safe, simple construction, high environmental protection, and energy-saving low-speed magnetic levitation rail vehicle, which is suitable for short-distance transportation of people or goods in cities and tourist attractions. transport. The main feature of the present invention is to use Bi-2223/Ag or other high-temperature superconducting wires instead of conventional wires to make magnets to achieve this purpose.

Prior to the present invention, the magnetic levitation rail vehicle can be divided into two types: the conventional electromagnetic attraction type and the magnetic repulsion type, according to the characteristics of the force between the magnetic levitation magnet and the track guide rail. The constant conduction electromagnetic attraction type EMS is also called the active attraction type. Its principle is to use a magnet wound with a conventional wire under the suspension and cooperate with an iron core to attract a ferromagnetic guide rail; the attraction is balanced with the gravity of the suspension; When there is a fixed gap between the magnet core and the ferromagnetic guide rail, the suspension can be suspended upside down. The height of the suspension gap is usually about 10mm. In order to maintain a constant suspension height, a sensor must be equipped to measure the change of the suspension gap. At the same time, an excitation current feedback system is used to control the height of the suspension gap to achieve stable suspension.

Its representative product is the Transrapid series models developed by German FRG company. The Transrapid-01 vehicle developed in 1971 weighed 5.8 tons and reached a speed of 90 km/h on a 660-meter-long experimental line. In the early 1980s, FRG built a 31-kilometer closed experimental line in Emsland. The model was also developed into the Transrapid-06 type. There are 2 compartments in the car body, which can carry 196 passengers, and the maximum speed can reach 400 km/h. During nearly ten years of trial operation, a total of 1 million kilometers has been traveled. In 2001, Germany's FRG company used this technology to build a 30-kilometer-long constant-conduction electromagnetic attraction line in Pudong, Shanghai and realized its first commercial operation, with a maximum speed of 500 km/h. Another representative constant conduction electromagnetic attraction maglev line is the HSST series sponsored by Japan Airlines. The HSST-01 series was successfully developed in 1978; the speed reached 307.8 kilometers per hour on a 1.3-kilometer experimental line. Among them, the manned HSST-03 series has achieved 1 million layoffs on a short-distance experimental line.

A common shortcoming of the above-mentioned maglev trains with magnets wound by conventional wires is that the levitation height is too low by about 10mm. This deficiency comes from the fact that the energy consumption of conventional wires limits the current-carrying capacity of the wires, which makes the magnets unable to provide enough attraction to the ferromagnetic track to achieve the purpose of increasing the levitation height. The poor current-carrying capacity of the wires and the low levitation height of the maglev train have brought a series of problems: due to the low levitation height, the requirements for the track infrastructure are increased; due to the resistance heating of the conventional wires, the volume and weight of the electromagnet are large , high energy consumption and low efficiency. In addition, this maglev train is designed to run at high speed, and has high requirements on the car body, track and control, which makes the structure of the whole system complex and expensive.

Based on this principle of magnetic levitation, considering reducing the energy consumption of conventional wires used in making magnets for magnetic levitation trains, Grumman Cooperation in the United States proposed a magnetic levitation method using low-temperature superconducting magnets mixed with conventional wire magnets in 1992. It works in A low-temperature superconducting magnet at liquid helium temperature is supplied with direct current to provide the main magnetic levitation force to reduce energy consumption. At the same time, there are two magnets wound by conventional wires in the magnetic circuit for attitude adjustment of the maglev train. In this design, the current change in the low-temperature superconducting magnet is always controlled within 1Hz, mainly because the non-ideal second-type superconductor working in the AC environment will have AC loss, and the heat caused by the AC loss will be Cause the temperature rise of the local working point of the magnet. Since the temperature of the working area of the low-temperature superconducting material is very low, the local temperature rise will quickly cause the local quenching of the superconducting wire for the preparation of the low-temperature superconducting magnet, and then cause the quenching of the entire magnet, and may even Burn the whole magnet. Therefore, the low-temperature superconducting magnet working in the liquid helium temperature zone cannot carry the AC current greater than 1Hz, and the general control signal frequency is between 1-1000Hz. That is to say, the low-temperature superconducting magnet cannot directly work in the available under control. At the same time, we must also consider the possible damage to the superconducting properties of the low-temperature superconducting coil due to the magnetic field generated by the additional conventional wire control coil. In order to keep the frequency of the current change in the low-temperature superconducting coil not higher than 1 Hz, it is necessary to equip the control circuit with related circuits, which also brings about complexity in the circuit. The disadvantages of high cost and poor stability brought about by the introduction of low-temperature equipment are also unavoidable in the magnetic levitation method of mixed use of low-temperature superconducting magnets and conventional wire magnets.

As opposed to the magnetic attraction method, there is also a levitation electric EDL, also known as a magnetic repulsion maglev solution. The levitation electric maglev uses a high magnetic field generated by a large low-temperature superconducting magnet to move under the metal guide rail under the car body. Or an eddy current is generated on the coil, and the magnetic field generated by the eddy current interacts with the magnetic field generated by the superconducting magnet to generate an upward repulsive force. The suspension height of this type of suspension can reach 30cm.

The representative product of the magnetic repulsion maglev train is the ML-100 series supported by the Japanese National Railway in the early 1970s. The world record for the fastest rail train at the time. In 1994, a 43-kilometer-long experimental line was built 128 kilometers west of Tokyo. Among them, the racetrack-shaped superconducting coil is wound with low-temperature niobium-titanium superconducting wire, and the superconducting coil generates a magnetic field of 2-3T. According to the Japanese National Railway plan, this line will become part of the Tokyo-Osaka commercial operation line in the future.

The disadvantage of the magnetic-repulsion maglev train is that the low-temperature superconducting wire works in the liquid helium temperature region. A refrigerator must be equipped during operation, and the introduction of the refrigerator will inevitably increase the size of the magnet and increase the cost of operation and maintenance. At the same time, because the magnetic repulsion type magnetic levitation method does not have a ferromagnetic medium to form a magnetic circuit, the magnetic field cannot be well restrained, and a part of the divergent magnetic flux will enter the interior of the passenger compartment, causing damage to the human body. Therefore, a magnetic shielding device is also required in the implementation of the magnetic repulsion type maglev train to prevent the divergent magnetic flux from causing damage to the human body, which will increase the complexity of the magnetic repulsion type magnetic levitation system.

In addition to the above two magnetic levitation methods, in March 2002, Southwest Jiaotong University in my country used the pinning effect of the YBCO high temperature superconducting block on the magnetic flux in the superconducting state to successfully develop the "Century" high temperature superconducting magnetic levitation The experimental vehicle was displayed at the "863" 15th Anniversary Achievement Exhibition. This high-temperature superconducting maglev test vehicle can take 5 people. The permanent magnet guide rail is 15.5 meters long and the maximum levitation weight is 700 kg. It is by far the world's largest manned high-temperature superconducting block maglev test vehicle.

The disadvantage of high-temperature superconducting bulk maglev vehicles is that the track is completely laid by permanent magnets, and the infrastructure cost for the track is too high. Moreover, the permanent magnet track will absorb stray ferromagnetic substances near the roadbed, and removing these substances will increase the line operation and maintenance costs, and it is very difficult. The ferromagnetic substances remaining on the track will increase the danger of the operation of the maglev vehicle. This kind of magnetic levitation formed by the magnetic flux pinning effect cannot realize the active control of the levitation height of the magnetic levitation experimental vehicle, which is also a shortcoming that the high temperature superconducting bulk magnetic levitation vehicle cannot overcome.

Considering the above factors, we propose a high-temperature superconducting magnet that uses high-temperature superconducting magnets to provide magnetomotive force and can withstand alternating current changes. The excitation current of the magnetizer is used to adjust the attractive force between the magnet and the ferromagnetic track, so as to actively control the levitation state of an electromagnetic attraction high-temperature superconducting magnetic levitation device. The device can be used as a transportation tool with low energy consumption, low vibration, low noise and environmental protection for city and sightseeing entertainment.

Contents of the invention

1. Purpose of the invention:

The purpose of the present invention is to realize a low energy consumption, low vibration, low noise and environment-friendly transportation tool for urban and sightseeing entertainment.

2. Invention features:

The invention relates to a high-temperature superconducting magnetic levitation device, which comprises a high-temperature superconducting magnet, a car body, a guide rail, a position sensor and a voltage-controlled current source. The present invention is characterized in that the high-temperature superconducting magnet made by winding high-temperature superconducting wires is controllable, and the frequency of the AC component of the control current is within the range of 0-1000 Hz. The voltage-controlled current source adopts the method of superposition of AC and DC, and the phase difference between the output AC current and the input AC voltage is not more than 10°. The voltage-controlled current source includes:

a. An operational amplifier and a power amplifier connected in series in sequence, wherein the input terminal of the operational amplifier is connected to the output terminal of the DC circuit, and the output terminal of the power amplifier is connected to the load;

b. Proportional differential operation circuit, its input end is connected with one end of the load, and its output end is connected with the other input end of the operational amplifier.

The high-temperature superconducting magnets are respectively located at the two ends of the lower side of the car body, and they are connected with the reinforcing parts for the car body. The high-temperature superconducting magnets each contain:

a. Iron core;

b. Cryogenic Dewar with liquid nitrogen inside. There are cylindrical holes on the low-temperature Dewar, and iron cores are filled in the cylindrical holes. The thickness of the low-temperature Dewar near the two arms of the iron core is slightly smaller than the thickness of its surroundings and bottom ;

c. The working temperature of the high-temperature superconducting coil is below 80K, and it is composed of multiple coaxial Bi-based high-temperature superconducting pie-shaped coils.

The iron core can adopt laminated U-shaped iron core. A pie coil is a solenoid-like coil wound from a single superconducting wire. The coils can be connected by soldering. The superconducting wire used in the high-temperature superconducting coil is any one of the Bi-2223/Ag superconducting tape or the film-coated YBCO series second-generation high-temperature superconducting tape. The guide rail in the present invention is reinforced by guide rail reinforcements, which are located parallel to the length direction of the car body, and have a fixed air gap with the two poles of the iron core in the above-mentioned high temperature superconducting magnet, and the bottom surfaces at the two ends of the two guide rails support rail frame. The position sensor can measure the change of the suspension gap in real time, and at the same time, the excitation current feedback system is used to control the height of the suspension gap to achieve stable suspension. The position sensor is an eddy current sensor, which is respectively fixed on the upper end surface of the guide rail and the high temperature superconducting magnet through the sensor bracket. The car body can be equipped with wheels to play a supporting role, or a permanent magnet can be installed to play a supporting role, or the wheels and permanent magnets can be used to play a supporting role simultaneously, and also can be supported without wheels.

2. Experiment proves that the present invention has the following advantages:

1. The high-temperature superconducting magnet of the present invention can work under an alternating signal, and adjust the attractive force between the magnet and the ferromagnetic track by controlling the excitation current flowing through the high-temperature superconducting magnet, thereby actively controlling the levitation state of the magnetic levitation device. Compared with people's knowledge that the change frequency of the excitation current flowing through the superconducting magnet is less than 1Hz; it is necessary to add a conventional wire magnet to realize the levitation state control of the maglev device, which undoubtedly greatly simplifies the vehicle maglev control system and reduces the control. The power and cost of the equipment can also further reduce the self-weight of the maglev car body.

2. The frequency bandwidth of the high-temperature superconducting magnet of the present invention is 0-1000 Hz when it works under the alternating signal, such a wide frequency band can quickly realize the position adjustment when the magnetic levitation device generates a small displacement.

3. The high-temperature superconducting magnet coil implemented by the present invention is characterized in that when the frequency of the current change of the control levitation height is less than 1000 Hz, the superconducting magnet current and the superconducting magnet magnetic field have only a magnetic field hysteresis of less than 10 degrees, so that it can be well realized Fast response of high temperature superconducting coil magnetic field to excitation current change. The block diagram of the control principle is shown in Figure 6.

4. The power supply that provides the high-temperature superconducting magnet excitation current has good AC characteristics. It has the following characteristics: ①In the range of 0-1000Hz, the AC output current amplitude meets the requirements for the high-temperature superconducting magnet inductive load excitation current; In the range of 0~1000Hz, the phase difference between the output AC current and the input AC voltage is not more than 10°; ③In the range of 0~1000Hz, the gain fluctuation between the output AC current and the input AC voltage does not exceed 5%. The principle wiring diagram of the power supply is shown in Figure 7.

5. The superconducting coil of the high-temperature superconducting magnet is made of high-temperature superconducting wires working in the liquid nitrogen temperature zone. The coils are prepared by single-wire double paralleling, solder joints, inter-turn insulation, and varnish fixation. As shown in Figure 8. It can also be prepared by a solenoid winding method that does not require welding. Compared with electromagnets wound with conventional copper wires, the energy loss of the excitation coil can be greatly reduced, and the weight and volume can be reduced.

6. The car body adopts a frame structure, which is made of light metal materials or non-metallic high-strength materials. While ensuring the structural strength, the weight of the car body is reduced, and the car body is more stable in motion through the use of suspension and shock absorption.

7. In order to increase the magnetic field strength of the high-temperature superconducting magnet, a U-shaped magnetic core is introduced to provide a magnetic circuit. Two high-temperature superconducting coils are placed on the two vertical arms of the U-shaped iron core, and can also be placed on the cross arm. The U-shaped iron core is fixed to the car body, and there is a gap between the two poles of the U-shaped iron core and the guide rail. The size of this gap is the suspension height that needs to be actively controlled. Providing the U-shaped magnetic core to the magnetic circuit will reduce the bad influence of divergent magnetic flux on other car body parts and objects carried by the magnetic levitation device. The position signal of the high-temperature superconducting magnetic levitation device can be obtained by distance, position or pressure sensors, and there are wide hardware options.

8. The material for winding the high-temperature superconducting coil is the Bi-based high-temperature superconducting wire that has been industrially produced. With the development of science and technology, the second-generation high-temperature superconducting tape-Y-series high-temperature superconducting wire will also be applicable to the present invention. This will help reduce the construction cost of the high-temperature superconducting maglev device.

9. The superconducting coil of the high temperature superconducting magnet is cooled by liquid nitrogen. Compared with the low-temperature superconducting magnetic levitation device working in the liquid helium temperature zone, the invented superconducting magnet refrigeration and heat insulation device is simple, economical, and works stably and reliably. The working environment of the high temperature superconducting magnet needs to be equipped with a low temperature dewar. As shown in Figure 9. The low-temperature Dewar of the magnetic levitation device of the present invention is made of polymer materials, and there are cylindrical holes on the low-temperature Dewar, and the U-shaped iron core passes through the cylindrical holes without contacting the cooling medium. The selection of materials will reduce material cost and processing difficulty, and this room temperature iron core structure can also save the cooling power required by superconducting magnets.

10. The invented superconducting maglev car body can be supported without wheels, or can be equipped with wheels, can also be installed with permanent magnets for support, and can also use wheels and permanent magnets for support at the same time. In the case of wheels, the role of the wheels can be to provide support in situations where the superconducting magnets are not effective, such as when parking or in the event of an accident. This reduces energy consumption and increases safety.

11. Where there are wheels, the role of the wheels can also be to bear part of the pressure during motion. This can make the superconducting magnetic levitation device of the present invention more simple, safe and reliable. Compared with conventional wheel-rail vehicles, the wheeled superconducting magnetic levitation device of the present invention has the advantages of low energy consumption, low noise and low vibration.

Description of drawings

Figure 1. Schematic diagram of the overall structure of the high-temperature superconducting magnetic levitation device.

Figure 2. A cross-sectional view of a high-temperature superconducting magnet including internal coils and a Dewar providing a cryogenic environment.

Fig. 3. Photos of an embodiment of a high-temperature superconducting magnetic levitation device.

Fig. 4. the structural diagram of embodiment 2 of the present invention.

Fig. 5. Structural diagram of Embodiment 3 of the present invention.

Figure 6. Schematic block diagram of a voltage-controlled current source.

Figure 7. Relational diagram of the main components of a voltage-controlled current source.

Fig. 8. Schematic diagram of superconducting magnet structure.

Figure 9. Schematic diagram of the cryogenic Dewar structure.

See Figure 1, 1 is the high temperature superconducting magnet, 2 is the car body, 3 is the guide rail, 4 is the power supply, 5 is the air gap sensor, 6 is the guide rail frame, 7 is the sensor bracket, 8 is the reinforced angle steel, 9 is the magnet and Body connectors.

As shown in Fig. 2, 10 is a U-shaped iron core, 11 is a low-temperature Dewar, and 12 is a high-temperature superconducting coil.

See Fig. 5, and 13 is a wheel, and 14 is a permanent magnet.

Detailed ways

Example 1

Embodiment 1 of a high-temperature superconducting magnetic levitation device As shown in Figure 1, embodiment 1 of a kind of high-temperature superconducting magnetic levitation device implemented by the present invention is a principle experimental car body, a kind of high-temperature superconducting magnetic levitation device. The high temperature superconducting magnet assembly 1 is connected to the vehicle body 2 through the magnet and the vehicle body connector 9 . The two steel guide rails 3 on both sides are placed on a frame made of angle steel. In order to prevent the deformation of the steel guide rail from being too large, we use reinforced angle steel 8 to connect with the frame. The air gap sensor 5 is integrated with the high temperature superconducting magnet assembly through the sensor bracket 7 . The air gap sensor 5 is an eddy current sensor, and the eddy current sensor detects the relative position between the HTS magnet assembly 1 and the surface of the steel guide rail 3, thereby reflecting the distance between the magnetic poles of the iron core and the lower surface of the rail in real time. Power supply 4 and other control components are placed above the car body. A current lead is connected to the vehicle power supply and the AC 220V mains.

The magnetic circuit composed of U-shaped iron core 10 , high temperature superconducting coil 12 and low temperature Dewar 11 is shown in FIG. 2 . As a complete magnetic circuit, a ferromagnetic guide rail 3 is also included above the poles of the U-shaped iron core. The high temperature superconducting coil 12 surrounds the two arms of the U-shaped iron core 10 and is close to the bottom of the Dewar. The U-shaped iron core 10 is made of 0.23mm thick silicon steel sheets which are wound, dipped in paint, and reinforced. The design of the laminated iron core is mainly to suppress the eddy current brought by the changing magnetic flux to the iron core. An air gap is formed between the two magnetic poles of the U-shaped iron core 10 and the ferromagnetic guide rail 3 . The high temperature superconducting coil 12 is isolated from the U-shaped iron core 10 by a low temperature Dewar 11 . The U-shaped iron core 10 is always in the working environment at room temperature. A high-temperature superconducting magnetic levitation device with a high-temperature superconducting coil 12 working state balance current of 3.2A, the levitation device can generate a magnetic flux density of 0.21T on the surface of an air gap of 5mm, and can generate a vertical levitation force of 72N on a ferromagnetic guide rail.

The high-temperature superconducting coil 12 is wound by a 61-core Bi-2223/Ag high-temperature superconducting tape, and the surface of the Bi-2223/Ag high-temperature superconducting tape is coated with insulating varnish to realize the winding of the high-temperature superconducting coil 12. For the insulation between turns, the thickness of the insulating varnish is less than 10 μm. The high-temperature superconducting coil 12 is formed by stacking three single-wire double-bake coils. There is no fixed central positioning axis physically between the three single-wire double pies, and the omission of the fixed positioning axis is to shorten the distance between the high-temperature superconducting coil 12 and the U-shaped iron core 10, thereby reducing magnetic flux leakage. Each wire cake needs 25 meters of Bi-2223/Ag high-temperature superconducting wire, and the entire coil uses 75 meters of Bi-2223/Ag high-temperature superconducting wire. There are three single-line double pies, and the connection between the pies is made by lap welding with ordinary Sn-Pb solder. The contact resistance between them can be precisely measured by the magnetic field attenuation method. Experiments show that the contact resistance of a welding point with an overlapping length of 2.6 mm can be controlled below 50 nanoohms. After the coil is wound, it needs to go through the overall dipping process to form a whole.

The high-temperature superconducting coil 12 implemented in the present invention adopts a dynamic performance testing method, which can effectively detect the inter-turn short circuit inside the high-temperature superconducting coil, and the magnetic field hysteresis caused by hysteresis and eddy current in the entire magnetic circuit . After measurement, the phase difference between the coil excitation current and the coil central point magnetic field formed by the coil excitation current is less than 5°.

The main starting point of the design of the low temperature Dewar 11 is to reduce the eddy current loss, for this purpose, all parts of the low temperature Dewar 11 are made of non-metallic materials. By foaming plastic in a mold, we can form a low-temperature Dewar at one time. The low-temperature Dewar 11 is shown in Figure 2. It is characterized by economical price, light weight, no eddy current and simple manufacturing process. The thickness of the low-temperature Dewar 11 close to the two arms of the U-shaped iron core is slightly smaller than the thickness of its surroundings and the bottom. The distance between the U-shaped iron cores 10 reduces magnetic flux leakage and improves work efficiency. The low-temperature Dewar 11 can contain 1.1L of liquid nitrogen, and can keep the high-temperature superconducting coil 12 working in a superconducting state for at least 1.5 hours when the high-temperature superconducting coil 12 has a balance current of 3.2A.

The drive, stop and speed control of a high-temperature superconducting magnetic levitation device can be realized by the interaction between the driving coil on the magnetic levitation device and the coupling coil on the track; it can also be realized by directly setting a linear motor on the track. The driving device of Embodiment 1 of a high-temperature superconducting magnetic levitation device is characterized in that: the driving device is 12 pairs of driving coils, and the phase difference between the driving currents of every two adjacent pairs of driving coils is 120 degrees. The reaction force generated by the induced current generated on the closed metal plate of the car body of the magnetic levitation device implements the drive and control of the high temperature superconducting magnetic levitation device.

Example 2

Embodiment 2 of a high-temperature superconducting magnetic levitation device As shown in Figure 1, embodiment 2 of a kind of high-temperature superconducting magnetic levitation device implemented by the present invention is a principle experiment car body, a kind of high-temperature superconducting magnetic levitation device. The high temperature superconducting magnet assembly 1 is connected to the vehicle body 2 through the magnet and the vehicle body connector 9 . The two steel guide rails 3 on both sides are placed on a frame made of angle steel. In order to prevent the deformation of the steel guide rail from being too large, we use reinforced angle steel 8 to connect with the frame. The air gap sensor 5 is integrated with the high temperature superconducting magnet assembly through the sensor bracket 7 . The air gap sensor 5 is an eddy current sensor, and the eddy current sensor detects the relative position between the HTS magnet assembly 1 and the surface of the steel guide rail 3, thereby reflecting the distance between the magnetic poles of the iron core and the lower surface of the rail in real time. Power supply 4 and other control components are placed above the car body. A current lead is connected to the vehicle power supply and the AC 220V mains.

The magnetic circuit composed of U-shaped iron core 10 , high temperature superconducting coil 12 and low temperature Dewar 11 is shown in FIG. 2 . As a complete magnetic circuit, a ferromagnetic guide rail 3 is also included above the poles of the U-shaped iron core. The high temperature superconducting coil 12 surrounds the two arms of the U-shaped iron core 10 and is close to the bottom of the Dewar. The U-shaped iron core 10 is made of 0.23mm thick silicon steel sheets which are wound, dipped in paint, and reinforced. The design of the laminated iron core is mainly to suppress the eddy current brought by the changing magnetic flux to the iron core. An air gap is formed between the two magnetic poles of the U-shaped iron core 10 and the ferromagnetic guide rail. The high temperature superconducting coil 12 is isolated from the U-shaped iron core 10 by a low temperature Dewar 11 . The U-shaped iron core 10 is always in the working environment at room temperature. A high-temperature superconducting magnetic levitation device with a high-temperature superconducting coil 12 working state balance current of 3.2A, the levitation device can generate a magnetic flux density of 0.21T on the surface of an air gap of 5mm, and can generate a vertical levitation force of 72N on a ferromagnetic guide rail.

The high-temperature superconducting coil 12 is wound by a 61-core Bi-2223/Ag high-temperature superconducting tape, and the surface of the Bi-2223/Ag high-temperature superconducting tape is coated with insulating varnish to realize the winding of the high-temperature superconducting coil 12. For the insulation between turns, the thickness of the insulating varnish is less than 10 μm. The high-temperature superconducting coil 12 is formed by stacking three single-wire double-bake coils. There is no fixed central positioning axis physically between the three single-wire double pies. The omission of the fixed positioning axis is to shorten the distance between the high-temperature superconducting coil 12 and the U-shaped iron core 10, thereby reducing magnetic flux leakage. Each wire cake needs 25 meters of Bi-2223/Ag high-temperature superconducting wire, and the entire coil uses 75 meters of Bi-2223/Ag high-temperature superconducting wire. There are three single-line double pies, and the connection between the pies is made by lap welding with ordinary Sn-Pb solder. The contact resistance between them can be precisely measured by the magnetic field attenuation method. Experiments show that the contact resistance of a welding point with an overlapping length of 2.6 mm can be controlled below 50 nanoohms. After the coil is wound, it needs to go through the overall dipping process to form a whole.

The high-temperature superconducting coil 12 implemented in the present invention adopts a dynamic performance testing method, which can effectively detect the inter-turn short circuit inside the high-temperature superconducting coil, and the magnetic field hysteresis caused by hysteresis and eddy current in the entire magnetic circuit . After measurement, the phase difference between the coil excitation current and the coil central point magnetic field formed by the coil excitation current is less than 5°.

The main starting point of the design of the low temperature Dewar 11 is to reduce the eddy current loss, for this purpose, all parts of the low temperature Dewar 11 are made of non-metallic materials. By foaming plastic in a mold, we can form a low-temperature Dewar at one time. The low-temperature Dewar 11 is shown in Figure 2. It is characterized by economical price, light weight, no eddy current and simple manufacturing process. The thickness of the low-temperature Dewar 11 close to the two arms of the U-shaped iron core is slightly smaller than the thickness of its surroundings and the bottom. The distance between the U-shaped iron cores 10 reduces magnetic flux leakage and improves work efficiency. The low-temperature Dewar 11 can contain 1.1L of liquid nitrogen, and can keep the high-temperature superconducting coil 12 working in a superconducting state for at least 1.5 hours when the high-temperature superconducting coil 12 has a balance current of 3.2A.

The main feature of Embodiment 2 of a high-temperature superconducting magnetic levitation device is that the weight of the car body is shared by the supporting force of the wheels and the attraction force of the electromagnet. The weight of the car body 2 is jointly borne by the contact support force between the wheels 13 and the guide rail 3 and the electromagnetic attraction force between the superconducting magnet 1 and the guide rail 3 . In the event that the vehicle is stationary or the superconducting magnet fails, the wheels 13 will bear all the weight of the vehicle body. Embodiment 2 of a high-temperature superconducting magnetic levitation device improves the safety of the high-temperature superconducting magnetic levitation system, and reduces the requirements for the reliability of automatic control of the air gap interval between the high-temperature superconducting magnet and the steel guide rail. Wheel 13 can be made of iron and can also be made of rubber.

The drive, stop and speed control of a high-temperature superconducting magnetic levitation device can be realized by the interaction between the driving coil on the magnetic levitation device and the coupling coil on the track; it can also be realized by directly setting a linear motor on the track. The driving device of Embodiment 2 of a high-temperature superconducting magnetic levitation device is characterized in that: the driving device is 12 pairs of driving coils, and the phase difference between the driving currents of each adjacent pair of driving coils is 120 degrees. The reaction force generated by the induced current generated on the closed metal plate of the car body of the magnetic levitation device implements the drive and control of the high temperature superconducting magnetic levitation device.

Example 3

An example 3 of a high-temperature superconducting magnetic levitation device is shown in FIG. 5 . On the basis of Embodiment 2, we added the permanent magnet 14 as a third means that can provide the suspension force in the vertical direction. The permanent magnet can be used as a part of the U-shaped iron core, integrated in a magnetic circuit, or used as a separate magnetic circuit.

Compared with the high-speed maglev train, one of the characteristics of the superconducting maglev device of the present invention is that the car body runs at a low speed; it is suitable for short-distance urban traffic, sightseeing and entertainment with low energy consumption, low vibration, low noise, and high environmental protection transportation tool, which will greatly reduce the technical and infrastructure costs of the superconducting magnetic levitation device.

Claims (10)

1. A high-temperature superconducting magnetic levitation device, which contains a high-temperature superconducting magnet, a car body, a guide rail, a position sensor and a voltage-controlled current source, is characterized in that the high-temperature superconducting magnet wound by a high-temperature superconducting wire can be Controlled, when the current change frequency for controlling the levitation height is less than 1000Hz, the superconducting magnet current and the superconducting magnetic field have only a magnetic field hysteresis of less than 10°. 2. The high-temperature superconducting magnetic levitation device according to claim 1, wherein the voltage-controlled current source adopts an AC-DC superposition mode, and the phase difference between its output AC current and the input AC voltage is not more than 10°, so The voltage-controlled current source described contains: a. An operational amplifier and a power amplifier connected in series in sequence, wherein the input terminal of the operational amplifier is connected to the output terminal of the DC circuit, and the output terminal of the power amplifier is connected to the load; b. Proportional differential operation circuit, its input end is connected with one end of the load, and its output end is connected with the other input end of the operational amplifier. 3. The high-temperature superconducting magnetic levitation device according to claim 1, wherein the high-temperature superconducting magnets are located at the two ends of the lower side of the car body respectively, and they are connected with the car body with reinforcements, and the high-temperature superconducting magnets Each contains: a. Iron core; b. Cryogenic Dewar with liquid nitrogen inside. There are cylindrical holes on the low-temperature Dewar, and iron cores are filled in the cylindrical holes. The thickness of the low-temperature Dewar near the two arms of the iron core is slightly smaller than the thickness of its surroundings and bottom ; c. The working temperature of the high-temperature superconducting coil is below 80K, and it is composed of multiple coaxial Bi-based high-temperature superconducting pie-shaped coils. 4. The high temperature superconducting magnetic levitation device according to claim 3, characterized in that a laminated U-shaped iron core is used. 5 . The high-temperature superconducting magnetic levitation device according to claim 3 , wherein the pie-shaped coil is a solenoid coil wound by a single superconducting wire. 6 . 6. The high temperature superconducting magnetic levitation device according to claim 3, wherein the coils are connected by soldering. 7. The high-temperature superconducting maglev device according to claim 3, characterized in that, the superconducting wire used in the high-temperature superconducting coil is the second generation of the YBCO series of Bi-2223/Ag superconducting tape or coating Any of the high temperature superconducting tapes. 8. The high-temperature superconducting magnetic levitation device according to claim 3, characterized in that, the guide rail is reinforced by a guide rail reinforcement, and it is parallel to the length direction of the vehicle body, and is connected to the iron core in the above-mentioned high-temperature superconducting magnet. There is a fixed air gap between the two poles, and the bottom surfaces at both ends of the two guide rails support the guide rail frame. 9. The high temperature superconducting magnetic levitation device according to claim 1, characterized in that the position sensor can measure the change of the suspension gap in real time, and simultaneously add an excitation current feedback system to control the height of the suspension gap to realize stable suspension, and the position sensor is a The eddy current sensor is respectively fixed on the upper end surface of the guide rail and the high temperature superconducting magnet through the sensor bracket. 10. The high-temperature superconducting magnetic levitation device according to claim 1, characterized in that, the car body is provided with wheels for support, or permanent magnets are installed for support, or both wheels and permanent magnets are used for support.

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