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.
World’s first cargo maglev system, the Electric Cargo Conveyor (ECCO) undergoes testing at the GA test track in San Diego, California. The system architecture is arranged to shuttle cargo vehicles back and forth through highspeed sections connected with dual-loading/unloading spurs. This arrangement, coupled with 20-sec headway between vehicles in transit and 2-min dwell time for loading and unloading, meets the 5,000 container trips per day requirement. The system is driverless, using automatic train control. It is also energy-efficient, and uses regenerative braking during deceleration.
Inductrack is a completely passive, fail-safe magnetic levitation system, using only unpowered loops of wire in the track and permanent magnets (arranged into Halbach arrays) on the vehicle to achieve magnetic levitation. The track can be in one of two configurations, a “ladder track” and a “laminated track”. The ladder track is made of unpowered Litz wire cables, and the laminated track is made out of stacked copper or aluminum sheets.
* Inductrack I was optimized for high speed operation
* Inductrack II, which is more efficient at lower speeds.
* Inductrack III for moving heavy freight
FIG. 4A shows a plot of drag power versus velocity for an Inductrack I configuration for a levitated load of 35,000 kg.
FIG. 4B shows a plot of drag power versus velocity for an Inductrack III configuration (such as that shown in FIG. 3) for a levitated load of 35,000 kg.
FIG. 5A shows a plot of drag power versus velocity for an Inductrack I configuration for a levitated “return trip” load of 8000 kg.
Several maglev railroad proposals are based upon Inductrack technology. The U.S. National Aeronautics and Space Administration (NASA) is also considering Inductrack technology for launching space planes.
General Atomics is developing Inductrak technology in cooperation with multiple research partners.
The only power required is to push the train forward against air and electromagnetic drag, with increasing levitation force generated as the velocity of the train increases over the loops of wire.
A new Inductrack configuration, herein referred to as “Inductrack III,” is described and is especially 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.
The new configuration also provides additional advantages over the Inductrack I configuration in that it makes it possible to increase the levitation efficiency (Newtons levitated per Watt of drag power) by factors of two or three for high-loads, and by even larger factors (four or five in typical cases) in low-load situations. Such a situation would occur in transporting loaded containers from a container ship to an inter-modal distribution center, and then returning the unloaded containers to the seaport.
In addition to increasing the levitation efficiency for both high- and low-load situations, the Inductrack III configuration permits a major reduction in the gap increase at low load. A large increase in gap is endemic to the Inductrack I configuration when it experiences a large reduction in the load it is carrying, such as would be the case for the container-ship service function described in the previous paragraph.
A further advantage of the new configuration is that it allows the dual-use of the “generator” section of the Inductrack III Halbach arrays. That is, the necessary windings for a linear synchronous motor (LSM) drive system could be piggy-backed on either side of the track assembly, where they would couple tightly to the strong transverse field component of the-dual Halbach array that comprises the generator section.
Another embodiment of the present invention employs mechanically adjustable bias permanent magnets to levitate a controlled portion of the load, thereby still further reducing the drag power compared to a simple Inductrack I system. The concept could also be employed to further increase the levitation efficiency of an Inductrack II system, with the adjustability feature being employed to optimize the performance.
FIG. 8A shows a plot of drag power vs velocity for an Inductrack I configuration having an 8000 kg load.
FIG. 8B shows a plot of drag power vs velocity for an Inductrack III configuration for an 8000 kg load.
FIG. 9A shows a comparison of drag power vs velocity comparing a modified Inductrack III configuration with a Davis formula for steel wheels on steel rails with a 35000 kg load.
FIG. 9B shows a comparison of drag power vs velocity comparing a Modified Inductrack III configuration with a Davis formula configuration all at a 8000 kg load.
Lawrence Livermore National Laboratory developed this improved maglev design. It 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.
*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.