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Inductrack

Lawrence Livermore National Laboratory

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Technology Marketing Summary

High reliability and lower maintenance and operating costs make magnetic levitation (maglev) technology integral to advancing the nation’s transportation networks.  In urban settings maglev has additional advantages over conventional mass transit and transport systems, including lower noise, higher efficiency, and higher grade and turn capabilities that allow vehicles to run on elevated tracks to eliminate the constraints and costs of underground tunnel operation.  Germany and Japan have developed large urban maglev transit systems, and other nations have maglev systems in development or on the drawing board.

Despite maglev’s compelling advantages, conventional maglev technologies have drawbacks.  Electromagnetic (EMS) maglev systems have problems with levitation instability.  Electrodynamic (EDS) maglev systems require magnetic shielding to protect onboard electronics, and energy efficiency is eroded by the cooling requirements of the cryogenic superconducting magnetic coils used in those systems. 

Description

Researchers at Lawrence Livermore National Laboratory have developed an improved maglev design that is more energy efficient and more stable than conventional maglev-based systems.  Inductrack, as the design is known, is a passive EDS system that uses Halbach arrays of permanent magnets for both levitation and propulsion.  Energy-intensive cryogenically cooled superconducting coils are eliminated, as are control electronics and hardware necessary to maintain stable levitation. 

In one design, Inductrack vehicles glide over track constructed with circuits that form a ladder-like array of “rungs” of cabled insulated wire.  As the vehicle moves over the track, Inductrack magnets induce a current in the track circuitry. This current generates a magnetic field that repels the magnet arrays. The result is levitation with greater inherent stability. Inductrack’s unique technology is safer, while saving energy and maintenance expenditures.  Several additional energy-efficient Inductrack designs have been developed for particular transit system applications.

Benefits
  • Immediate energy efficiencies are achieved because electrically-powered cryogenics are not required for Inductrack designs.
  • Inductrack replaces the electromagnets in conventional systems with permanent magnets, which don’t require a power source in order to generate a magnetic field.
  • Further savings come continuously since electrodynamic maglev designs like Inductrack do not require powered feedback control systems to stabilize levitation.
  • As a maglev system, Inductrack allows for a short turning radius and is designed for quiet operation.
  • Maintenance requirements for Inductrack are lower than they are for other maglev systems.
  • Onboard electronics and passengers with electromagnetic medical implants are unaffected by Inductrack’s magnetic fields.
  • Weather and temperature variations do not impair Inductrack’s levitation tolerances.
  • The Inductrack design is safer in the event of a power interruption. 
Applications and Industries
  • Inductrack improve the performance of EDS maglev systems serving both high-speed (intercity) and low-speed (urban) networks.
  • The Halbach array is well known for its ability to focus accelerator article beams, and the magnet configuration used in Inductrack may have additional applications in high-energy-field research.
  • The Inductrack levitation/propulsion capability has potential application in launching commercial payloads into earth orbit.  Accelerating a launch vehicle using Inductrack principles can reduce the fuel load requirements by 30–40%.
  • Inductrack would enable efficient and speedy inter-city transport of high-value packages and other deliverables.
More Information Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Date
Patent 6,629,503
Patent
6,629,503
Inductrack configuration
A simple permanent-magnet-excited maglev geometry provides levitation forces and is stable against vertical displacements from equilibrium but is unstable against horizontal displacements. An Inductrack system is then used in conjunction with this system to effect stabilization against horizontal displacements and to provide centering forces to overcome centrifugal forces when the vehicle is traversing curved sections of a track or when any other transient horizontal force is present. In some proposed embodiments, the Inductrack track elements are also employed as the stator of a linear induction-motor drive and braking system.
Lawrence Livermore National Laboratory 10/07/2003
Issued
Application 20100176674
Application
20100176674
Gear Trains Employing Magnetic Coupling
A first movable element includes a first Halbach array permanent magnet array. A second movable element placed in operable proximity to said first Halbach array includes a second Halbach array permanent magnet array. The first Halbach array is configured to transmit torque upon movement to the second movable element by magnetic force, wherein the torque is transferred with no physical contact occurring between the first movable element and the second movable element.
Lawrence Livermore National Laboratory 01/14/2010
Filed
Patent 7,096,794
Patent
7,096,794
Inductrack configuration
A simple permanent-magnet-excited maglev geometry provides levitation forces and is stable against vertical displacements from equilibrium but is unstable against horizontal displacements. An Inductrack system is then used in conjunction with this system to effect stabilization against horizontal displacements and to provide centering forces to overcome centrifugal forces when the vehicle is traversing curved sections of a track or when any other transient horizontal force is present. In some proposed embodiments, the Inductrack track elements are also employed as the stator of a linear induction-motor drive and braking system.
Lawrence Livermore National Laboratory 08/29/2006
Issued
Patent 6,633,217
Patent
6,633,217
Inductrack magnet configuration
A magnet configuration comprising a pair of Halbach arrays magnetically and structurally connected together are positioned with respect to each other so that a first component of their fields substantially cancels at a first plane between them, and a second component of their fields substantially adds at this first plane. A track of windings is located between the pair of Halbach arrays and a propulsion mechanism is provided for moving the pair of Halbach arrays along the track. When the pair of Halbach arrays move along the track and the track is not located at the first plane, a current is induced in the windings and a restoring force is exerted on the pair of Halbach arrays.
Lawrence Livermore National Laboratory 10/14/2003
Issued
Patent 6,250,230
Patent
6,250,230
Apparatus and method for reducing inductive coupling between levitation and drive coils within a magnetic propulsion system
An apparatus and method is disclosed for reducing inductive coupling between levitation and drive coils within a magnetic levitation system. A pole array has a magnetic field. A levitation coil is positioned so that in response to motion of the magnetic field of the pole array a current is induced in the levitation coil. A first drive coil having a magnetic field coupled to drive the pole array also has a magnetic flux which induces a parasitic current in the levitation coil. A second drive coil having a magnetic field is positioned to attenuate the parasitic current in the levitation coil by canceling the magnetic flux of the first drive coil which induces the parasitic current. Steps in the method include generating a magnetic field with a pole array for levitating an object; inducing current in a levitation coil in response to motion of the magnetic field of the pole array; generating a magnetic field with a first drive coil for propelling the object; and generating a magnetic field with a second drive coil for attenuating effects of the magnetic field of the first drive coil on the current in the levitation coil.
Lawrence Livermore National Laboratory 06/26/2001
Issued
Patent 5,722,326
Patent
5,722,326
Magnetic levitation system for moving objects
Repelling magnetic forces are produced by the interaction of a flux-concentrated magnetic field (produced by permanent magnets or electromagnets) with an inductively loaded closed electric circuit. When one such element moves with respect to the other, a current is induced in the circuit. This current then interacts back on the field to produce a repelling force. These repelling magnetic forces are applied to magnetically levitate a moving object such as a train car. The power required to levitate a train of such cars is drawn from the motional energy of the train itself, and typically represents only a percent or two of the several megawatts of power required to overcome aerodynamic drag at high speeds.
Lawrence Livermore National Laboratory 03/03/1998
Issued
Patent 6,664,880
Patent
6,664,880
Inductrack magnet configuration
A magnet configuration comprising a pair of Halbach arrays magnetically and structurally connected together are positioned with respect to each other so that a first component of their fields substantially cancels at a first plane between them, and a second component of their fields substantially adds at this first plane. A track of windings is located between the pair of Halbach arrays and a propulsion mechanism is provided for moving the pair of Halbach arrays along the track. When the pair of Halbach arrays move along the track and the track is not located at the first plane, a current is induced in the windings and a restoring force is exerted on the pair of Halbach arrays.
Lawrence Livermore National Laboratory 12/16/2003
Issued
Patent 6,758,146
Patent
6,758,146
Laminated track design for inductrack maglev systems
A magnet configuration comprising a pair of Halbach arrays magnetically and structurally connected together are positioned with respect to each other so that a first component of their fields substantially cancels at a first plane between them, and a second component of their fields substantially adds at this first plane. A track is located between the pair of Halbach arrays and a propulsion mechanism is provided for moving the pair of Halbach arrays along the track. When the pair of Halbach arrays move along the track and the track is not located at the first plane, a current is induced in the windings and a restoring force is exerted on the pair of Halbach arrays.
Lawrence Livermore National Laboratory 07/06/2004
Issued
Patent 8,985,030
Patent
8,985,030
Inductrack III configuration--a maglev system for high loads
Inductrack III configurations are suited for use in transporting heavy freight loads. Inductrack III addresses a problem associated with the cantilevered track of the Inductrack II configuration. The use of a cantilevered track could present mechanical design problems in attempting to achieve a strong enough track system such that it would be capable of supporting very heavy loads. In Inductrack III, the levitating portion of the track can be supported uniformly from below, as the levitating Halbach array used on the moving vehicle is a single-sided one, thus does not require the cantilevered track as employed in Inductrack II.
Lawrence Livermore National Laboratory 03/24/2015
Issued
Technology Status
Development StageAvailabilityPublishedLast Updated
PrototypeAvailable04/03/201204/03/2012

Contact LLNL About This Technology

To: Genaro Mempin<mempin1@llnl.gov>