Hybrid electrodynamic levitation system

A hybrid electrodynamic levitation system that utilizes both superconducting and conductive tracks. The hybrid system reduces the overall drag induced upon the system and reduces the amount of power required to achieve operating speeds, while resolving the issue of requiring velocity relative to the track for levitation. The total initial and operating costs of the hybrid system can be lower than utilizing a superconductive or conductive track alone, while still enabling a fail-safe levitation system for high speed transportation.

BACKGROUND

The present disclosure relates to levitation system.

2. Description of the Related Art

Conventional passive electrodynamic suspension (EDS) levitation systems suffer from multiple drawbacks.FIG. 1illustrates a conventional system utilizing permanent magnets for levitation of a vehicle on a conductive track and requiring motion of the vehicle relative to the conductive track to achieve a levitation force. This motion drives a requirement for the inclusion of wheels, or another means to prevent the levitation module from contacting the surface of the track when travelling at speeds lower than the velocity at which levitation occurs.

Moreover, due to the creation and dissipation of eddy currents within the conductive plate in the conductive track (originating from the changing magnetic field over the surface of the conductive plate) a magnetic drag force resists the forward motion of the vehicle.FIG. 2illustrates the drag force increases and peaks at velocities around 10 mph, and then sharply decreases as the relative velocity increases. A large amount of power is required to overcome this drag force at relatively lower speeds (as compared to “cruise speeds” that are expected for use in high speed transport).

Systems that utilize tracks including a high temperature superconductive material are efficient, but extremely costly. While there is no magnetic drag associated with permanent magnets levitating over a superconductive track, there are small losses due to imperfections in the permanent magnetic field. The cost of the superconductive material for the entire length of the track, along with the cooling power associated with maintaining the entire track under a critical temperature required to achieve superconductivity, leads to high initial and operating costs that render conventional superconducting track technology unfeasible for longer routes.

What is needed then, is a magnetic levitation rail system that is more energy and cost efficient as compared to a magnetic levitation rail system using conductive plates or superconductors. The present disclosure satisfies this need.

SUMMARY

The present disclosure describes a hybrid rail for a railway track. The rail comprises a first portion connected to a second portion, wherein the first portion includes a superconductor and the second portion includes a conductor. A vehicle magnetically coupled to a track including the rail levitates relative to the first portion when a first magnetic field interacts with a second magnetic field. The first magnetic field is generated using the superconductor in a superconductive state and the second magnetic field generated from a magnet attached to the vehicle. The vehicle levitates relative to the second portion when the second magnetic field interacts with the conductor.

The rail can be embodied in many ways including, but not limited to, the following examples.

1. The rail wherein the first portion has a first tapered end and the second portion has a second tapered end, so that the first tapered end mates effectively with the second tapered end.

2. The rail of one or any combination of the previous examples includes the first portion comprising an evacuated double walled tube having a first wall and second wall. The first wall forms/encloses a first volume, and the first wall and the second wall form/enclose a second volume between the first and second wall. The superconductor is disposed in the first volume and the second volume comprises a vacuum.

3. In yet another example, the first portion of one or any combination of the previous examples includes the superconductor comprising a plurality of YBaCuO crystals.

4. In a further example, the conductor and the magnet of one or any combination of the previous examples are disposed so as to form an electromagnetic suspension system (EMS) so that the vehicle levitates L in response to a second lift force generated when the second magnetic field interacts with the conductor comprising a ferromagnetic material.

5. In yet another example, the conductor and the magnet of one or any combination of examples 1-3 are disposed so as to form an electrodynamic suspension system EDS so that the vehicle1110levitates in response to a second lift force F2generated according to Lenz's law and a Lorentz force.

7. In a further example, the conductor of one or any combination of the previous examples comprises a solid conductive plate including slots and rungs.

8. In yet another example, the second portion of one or any combination of the previous examples comprises a laminate, the laminate including the conductor disposed as conductive material separated by an insulator.

9. In a further example, the magnet of one or any combination of the previous examples is disposed in a Halbach array.

10. In a yet another example the first portion of one or any combination of the previous examples has a length in a range of 100 feet-2000 feet.

11. In yet a further example, the first portion of one or any combination of the previous examples has a length sufficiently long for the vehicle to reach a speed, when entering the second portion from the first portion, such that the vehicle experiences a lift to drag ratio exceeding the maximal lift to drag ratio of the second portion.

12. In yet another example, the length in example 11 is such that the vehicle accelerates with a maximum acceleration of 1 g from an initial speed of 0 mph at one end of the first portion to a speed of at least 100 miles per hour at the other end of the first portion connected to the second portion.

13. A rail system including the rail of one or any combination of the previous example, wherein the first portion comprises less than 0.1% of an entire length of track in the rail system.

14. The rail system of example 13, further comprising a computer configured to control a speed of the vehicle on the rail system, wherein the speed when entering the second portion from the first portion is such that the vehicle experiences a lift to drag ratio of at least 100 or exceeding the maximal lift to drag ratio of the second portion304.

15. The rail of one or any combination of the previous examples, wherein the first portion includes a first section and a second section and the second portion between the first section and the second section.

16. The rail of one or any combination of the previous examples, wherein the vehicle comprises a passenger train.

The present disclosure further describes a method of operating a vehicle, comprising operating the vehicle on a track including a rail, the rail including a first portion connected to a second portion, and the first portion including a superconductor and the second portion including a conductor. The vehicle magnetically coupled to the track:

(1) levitates relative to the first portion in response to a first lift force generated when a first magnetic field generated using the superconductor in a superconductive state interacts with a second magnetic field generated from a magnet attached to the vehicle, and

(2) levitates relative to the second portion in response to a second lift force generated when the second magnetic field interacts with the conductor.

The present disclosure further describes a vehicle, comprising a magnet attached to a passenger cabin, the magnet generating a magnetic field interacting with a rail including a first portion connected to a second portion, the first portion including a superconductor and the second portion including a conductor; and a computer system connected to the vehicle controlling a speed of the vehicle. The vehicle:

(1) levitates relative to the first portion in response to a first lift force generated when a first magnetic field generated using the superconductor in a superconductive state interacts with a second magnetic field generated from a magnet attached to the vehicle,

(2) levitates relative to the second portion in response to a second lift force generated when the second magnetic field interacts with the conductor, and

(3) has a speed entering the second portion from the first portion such that lift to drag ratio associated with the vehicle is at its maximum value for the second portion of the track.

DESCRIPTION

In the following description, reference is made to the accompanying drawings which form a part hereof, and which is shown, by way of illustration, several embodiments. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure.

Technical Description

Hybrid Track Including a Superconductive Track Region and a Conductive Track Region

FIG. 3Aillustrates a rail300including a first portion302connected to a second portion304, the first portion302including a superconductor306and the second portion304including a conductor308. A vehicle magnetically coupled to a track310including the rail300levitates relative to the first portion in response to a first lift force F1generated when a first magnetic field M1(generated using the superconductor in a superconductive state) interacts with a second magnetic field M2(generated from a magnet attached to the vehicle). The vehicle levitates relative to the second portion in response to a second lift force F2generated when the second magnetic field M2interacts with the conductor in the second portion.

Also shown is a transition zone312between first portion and the second portion. In the transition zone312, the first portion302connects to an outside314of the second portion304so as to increase lift stability on the outside of the track. The amount of the first portion in the transition zone is reduced moving towards the second portion. In the example transition zone illustrated inFIG. 3A, the first portion has a first tapered end316, the second portion has a second tapered end318, and the first tapered end mates with/is physically attached to the second tapered end318. More specifically, as viewed from the top, the first tapered end comprises a first triangular cross-section320having a first hypotenuse322in a plane comprising a first surface324, the second tapered end comprises a second triangular cross section326having a second hypotenuse328in a plane comprising a second surface330, and the first surface324mates or is attached to the second surface330. In one or more examples, the transition zone has a length of 50-200 feet (e.g., 75 feet).

FIG. 3Billustrates a rail system300bcomprising a track including the conductive portion (second portion304) in between or in the middle of two superconductive portions (first section332and second section334). In other words, the first portion302comprises the first section332and second section334and the second portion304is between (or in the middle of) the first section332and second section334.

The lengths of the superconductive tracks (first and second sections of the track) are determined by how long it takes the vehicle traveling on the superconductive track to reach speeds higher than the peak drag value. However, in typical examples, the first portion comprising the superconductive track is shorter than the second portion comprising the conductive track. The superconductive track (first and second sections) are acceleration zones at the beginning and end of the track that (1) allow for levitation of the vehicle with no relative velocity of the vehicle relative to the track, thereby eliminating the need for wheels or additional means of rolling, and (2) increase efficiency of acceleration by eliminating magnetic drag force. In one example, assuming a maximum acceleration value of 1 g to ensure passenger comfort, a speed exceeding 100 mph is achieved after travelling approximately 300 or 400 feet on the first portion including superconductive track. This high speed exceeding 100 mph ensures an adequately high lift to drag ratio when entering into the conductive track (middle or second portion) from the first portion comprising superconductive track.

In one example that seeks to minimize costs, the lengths of the first and second sections including the superconductive track are a minute percentage (<0.1%) of the entire length of the track so as to minimize cost and energy consumption (e.g., due to cooling requirements for the superconductive track). In one or more examples, the conductive track (second portion) has a length of at least 300 miles.

Superconductive Track Example

In one or more examples, the first portion comprising the superconductive region of track requires cooling e.g., using liquid nitrogen or a refrigeration cycle. For example, liquid nitrogen with a boiling point of 77 K can be used to cool the superconductor (e.g., high temperature superconductive material, e.g., YBaCuO superconductors that maintain superconductivity at temperatures lower than 92 K). Refueling of the liquid nitrogen or additional power can be used to keep the superconductive track beneath the critical temperature required to maintain the superconductive state of the superconductor.

FIG. 4illustrates the first portion302of track includes a cryostat/cryostat chamber400comprising an evacuated double walled tube402having a first wall404and second wall406. The first wall forms or encloses a first volume408, and a second volume410is formed or enclosed between the first wall and the second wall. In one or more examples, the cryostat and walls404,406are fabricated from stainless steel.

The superconductor comprising superconductive material412is disposed or contained in the first volume.FIG. 4further illustrates the cryostat housing superconductive material including superconductive crystals414disposed in a grid like fashion. The sizing of the superconductive crystals is based on the optimal grain size of the superconductive material. In one example, the crystals are YBaCuO crystals that are approximately 2.5″×1.25″×0.5″.

The second volume between the first and second walls is evacuated so as to form vacuum450insulation which eliminates nearly all heat transfer. The additional low pressure environment in the second volume in the tube also results in decreased heat convection from the outside environment, thereby aiding in keeping the track at low temperatures. The cryostat can be actively cooled using refrigeration technology (the expected power consumption for actively cooling is on the order of 1-5 kilowatts for a total of 1200 ft of cooled track, corresponding to between 0.5-5 Watts per foot) or refilled with liquid nitrogen as needed. In one example, the first volume also contains the coolant (e.g., liquid nitrogen or other refrigerant) used to cool the superconductive material into a superconducting state. A valve can be connected to the first volume and configured to receive and transfer the coolant into the first or second volume.

The superconductive track width can be scaled with the size of the levitated mass. A track designed to be approximately 12 inches in width can levitate a 40,000 pound (lb) vehicle (although track width doesn't impact the weight of vehicle that can be levitated, since the longer the vehicle, the heavier the vehicle that can be levitated.

Conductive Track Region

The main portion (second portion304) of the track is comprised of a low cost conductive track that is optimized for a high lift to drag ratio. The track may be slotted or laminated to increase the inductance and therefore the lift to drag ratio, for example.

FIG. 5illustrates a slotted track500embodiment comprised of a solid conductive plate502with a machined out geometry. The geometry of the slots504and rungs506that comprise the track can be optimized in relation to the magnet geometry, vehicle speed, and desired lifting force. Example dimensions include, but are not limited to, a slot width WSLOTand a slot length LSLOTin a range of 1-2 feet, a rung length (Lrung) in a range of 0.2-0.75 feet, and a track width Wtrackin a range of 0.5-3 feet. Example materials for the conductive plate include, but are not limited to, aluminum. Example lift to drag ratios of at least 50 have been measured using this track configuration.

FIG. 6illustrates a laminated track600example comprised of conductive material602(e.g., aluminum) separated every few mm (e.g., spacing in a range of 1-10 mm) by a nonconductive material or insulator604such as, but not limited to, thin plastic sheets or anodized aluminum. Example dimensions for the laminated track include, but are not limited to, a track width Wtrack in a range of 0.5-2 feet (e.g., 1 foot). Theoretical lift to drag ratios for these dimensions exceed 150 at speeds greater than 100 mph. The spacing S between the conductive material can be set so as to localize the eddy currents.

Implementation of the conductive track is extremely cost efficient in comparison to the use of superconductive track. The use of a conductive track in the high speed portions of the track leads to a smaller amount of losses due to magnetic drag, but also provides a fail-safe mode of levitation. If power to the track or vehicle is lost, the vehicle will continue stable levitation until it reaches speeds of around 10 mph.

Example Vehicle

FIG. 7illustrates a vehicle700or passenger train700aincluding the vehicle (e.g., passenger cabin700bor train engine700c) comprising magnetic modules750including magnets702configured to generate a magnetic field M2that interacts with the track so as to levitate the vehicle above the track. In the example ofFIG. 7, the magnetic field M2that allows for magnetic levitation is generated by an array of permanent magnets702on the vehicle that are oriented in a “Halbach array”. The magnetic modules750including the one or more magnets702are attached (connection752) to the vehicle700.FIG. 8illustrates the Halbach array800is a certain configuration of permanent magnets that augments the magnetic flux density on one side of the array, and nearly negates it on the other. The Halbach array is oriented on the vehicle700such that the augmented magnetic field is interacting with the surface of the track310. In one or more examples, the magnets disposed in the Halbach array comprise an alloy of neodymium, iron, and boron.

The Halbach array800can be optimized with longer wavelengths to increase the lift to drag ratio of the levitation system (wherein wavelength defined as the length between repeating sections of a Halbach array, as shown inFIG. 9).FIG. 10illustrates lift to drag ratio as a function of wavelength of the Halbach array and speed, for different types of conductive track.

The implementation of the Halbach array allows for a higher levitated mass per magnet mass, as it increases the efficiency (magnetic flux per unit mass) of the permanent magnets. The orientation and positioning of the magnets can be optimized for use with the conductive track and will still perform adequately during their interaction with the superconductor in the superconductive track (first portion).

Example Rail Systems: Vacuum Tube Train (Vactrain)

FIGS. 11A-11Cillustrate the conductive region or portion (second portion304) of the hybrid track310in a vacuum tunnel1100(i.e., the vehicle comprises a passenger train travelling on a track310in an evacuated tunnel to further reduce drag).

FIG. 11Aillustrates a rail (300) wherein the conductor (308) and the magnet (702) are disposed so as to form an electromagnetic suspension system (EMS) so that the vehicle (1104) levitates (L) when the second magnetic field (M2) interacts with the conductor (308) comprising a ferromagnetic material (1150). In one or more examples, the magnets include electromagnets1102attached to the vehicle1104, the electromagnets interfacing with the conductive track (second portion304) comprising a (e.g., laminated ferromagnetic) track1106. In one or more examples, the electromagnets are actively controlled to provide a gap between the track1106and the magnets ranging from 1-4 cm. Feedback from proximity sensors feeds into electromagnets to maintain a constant gap. The electromagnets can be powered with a superconducting coil (reducing the energy requirement) and additional coils can be positioned to improve stability. Since the electromagnetic suspension system utilizes an attractive magnetic force between the conductive track1106and the electromagnets1102, the track1106must be above the electromagnets. The attractive magnetic force between the electromagnets and the ferromagnetic track decays exponentially with increasing distance from the steel track. Although the example ofFIG. 11Aillustrates the conductive track including a laminated ferromagnetic track, other ferromagnetic tracks can be used. The lift to drag ratio can range from 20 (for a solid ferromagnetic track) to (theoretically 100 or more using a laminated track).

FIG. 11Billustrates a rail (300) wherein the conductor (308) and the magnet (702) are disposed so as to form an electrodynamic suspension system (EDS) so that the vehicle (1110) levitates in response to a second lift force F2generated according to Lenz's law and a Lorentz force. In one or more examples, the magnets1108on the vehicle1110interface with the conductive track1112(second portion304). In an example passive system, permanent magnets are mounted on the vehicle in a single sided Halbach array with the conductive track1112including a ladder or Inductrack track surface as illustrated inFIG. 5orFIG. 6for example. In another example passive system, permanent magnets are mounted on the vehicle in a double Halbach array (Null Flux) with the conductive track including a ladder or Inductrack track surface. In yet another example passive system, permanent magnets are mounted on the vehicle in a single sided Halbach array with the conductive track comprising loops (Null Flux). In one example, the rail comprises6061aluminum (exampled dimensions include, but are not limited to, a track having a width of 12 feet and a thickness of 0.25 feet).

Without being bound by a particular scientific theory, the electrodynamic suspension system operates using Lenz's Law and the Lorentz Force, wherein a change in magnetic field in the conductive surface of the conductive track1112(caused by motion of magnets in the vehicle over the conductive track) generates eddy currents. The change in magnetic field in turn creates a magnetic field that opposes the change in magnetic field induced upon it. This causes opposing forces resulting in levitation of the vehicle.

In one or more examples, the EDS system exhibits a lift to drag ratio of 20, the gap between the vehicle and the conductive track is approximately 10 mm and the ratio of the mass of the vehicle to the magnet mass is 50:1.

Process Steps

FIG. 12is a flowchart illustrating a method of making and/or operating a rail system.

Block1200represents obtaining or providing (e.g., assembling or laying) a track comprising a rail, the rail including first portion connected to a second portion, the first portion including a superconductor and the second portion including a conductor. In one or more examples, the first portion (302) has a first tapered end (316) and the second portion (304) has a second tapered end (318), and the first tapered end (316) mates with the second tapered end (318). In this way, the first portion302connects to an outside314of the second portion304so as to increase lift stability on the outside of the track.

Examples of superconductor include, but are not limited to, YBaCuO superconductive material or other high-temperature superconductive materials.

In one or more examples, the conductor308comprises a solid conductive plate502including slots504and rungs506.

In one or more examples, the second portion304comprises a laminate650, the laminate650including the conductor308disposed as conductive material602separated by an insulator604.

Example lengths L2for the first portion include, but are not limited to, a length L2in a range of 100 feet-2000 feet or a length L2sufficiently long for the vehicle700to reach a speed, when entering the second portion304from the first portion302, such that the vehicle700experiences a lift to drag ratio exceeding the maximal lift to drag ratio of the second portion (e.g., more than 100). In one or more examples, the length L2is such that the vehicle700accelerates with a maximum acceleration of 1 g from an initial speed or velocity of 0 mph at one end360of the first portion302to a speed/velocity of at least 100 miles per hour at the other end362of the first portion302connected to the second portion304. In one or more further examples, the first portion302comprises less than 0.1% of an entire length L3of track310in the rail system300b.

Block1202represents optionally magnetically coupling a vehicle700to the track310, wherein the vehicle comprises700a magnet702attached to the vehicle700. In one or more examples, the magnet702comprises a rare earth permanent magnet (e.g., a magnet comprising an alloy of neodymium, iron, and boron). The magnet702generates a magnetic field M2interacting with the rail300(first portion302or second portion304).

Block1204represents optionally allowing the vehicle700to levitate L relative to the first portion302in response to a first lift force F1generated when a first magnetic field M1(generated using the superconductor306in a superconductive state) interacts with a second magnetic field M2generated from the magnet702attached to the vehicle700.

A propulsion system connected to the vehicle700controls a speed/velocity of the vehicle700guided along the track310by the rails300.

Block1206represents optionally allowing the vehicle700to levitate L relative to the second portion304in response to a second lift force F2generated when the second magnetic M2field interacts with the conductor308.

A computer system1300connected to the vehicle700controls a speed of the vehicle700so that the vehicle700has a speed or velocity (entering the second portion304from the first portion302) such that lift to drag ratio associated with the vehicle700is at its maximum value for the second portion304.

Processing Environment

FIG. 13illustrates an exemplary system1300used to implement processing elements needed to control the speed of the vehicle1314,700so that the lift to drag ratio entering the conductive portion of the track is sufficiently high (e.g., greater than 100).

The computer1302comprises a processor1304(general purpose processor1304A and special purpose processor1304B) and a memory, such as random access memory (RAM)1306. Generally, the computer1302operates under control of an operating system1308stored in the memory1306, and interfaces with the user/other computers to accept inputs and commands (e.g., analog or digital signals from the crew or automatic ice detector) and to present results through an input/output (I/O) module1310. The computer program application1312accesses and manipulates data stored in the memory1306of the computer1302. The operating system1308and the computer program1312are comprised of instructions which, when read and executed by the computer1302, cause the computer1302to perform the operations and/or methods herein described. In one embodiment, instructions implementing the operating system1308and the computer program1312are tangibly embodied in the memory1306, thereby making one or more computer program products or articles of manufacture capable of controlling the speed of the vehicle on the hybrid track as described herein. As such, the terms “article of manufacture,” “program storage device” and “computer program product” as used herein are intended to encompass a computer program accessible from any computer readable device or media.

Those skilled in the art will recognize many modifications may be made to this configuration without departing from the scope of the present disclosure. For example, those skilled in the art will recognize that any combination of the above components, or any number of different components, peripherals, and other devices, may be used.

Advantages and Improvements

The implementation of a hybrid superconductive/conductive track according one or more examples described herein solves the following problems:The requirement for wheels or additional means to prevent contact of levitation modules with the track and which slows the vehicle down. Vehicles described herein that do not require wheels assist with the acceleration of the vehicle.Decreased efficiency due to low lift to drag ratio. Embodiments of the rail system described herein aids acceleration of vehicles (e.g., in evacuated tubes) by ensuring that the vehicle enters the conductive region with an adequately high lift to drag ratio. Embodiments of the rail system described herein increase the efficiency of acceleration to cruise speeds by at least 50%.High costs. Embodiments of the rail system described herein reduce both overall initial and operating costs.Levitation failure. Embodiments of the hybrid rail system described herein enable fail-safe levitation in high-speed regions.

CONCLUSION

This concludes the description of the preferred embodiments of the present disclosure. The foregoing description of the preferred embodiment has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of rights be limited not by this detailed description, but rather by the claims appended hereto.