Researchers from the US Department of Energy’s Sandia National Laboratories have been given funding to develop Seraphim, a powerful motor that will be expected to enable trains to climb mountains without losing traction.
The Seraphim motor – an acronym for Segmented Rail Phased Induction Motor – is expected to be a simpler, less expensive alternative to the magnetically levitated (maglev) trains of Europe and Japan and has already proved itself in satellite launches.
The fiscal year 2001 Transportation Appropriations Bill passed by the US Congress allocates $2 million to Sandia for further motor testing and design of its Seraphim technology, which relies upon magnetic repulsion to push a vehicle forward.
The Seraphim motor works by sequentially powering a series of electromagnetic coils mounted on the vehicle. The powered coils induce associated eddy currents and magnetic fields of opposite direction in passive coils incorporated in the guideway.
The resultant repulsion of the magnetic fields accelerates the transit vehicle. Sensors monitor the location of the coils on the vehicle with respect to the coils in the guideway and control the sequential firing of the powered coils to produce either acceleration or braking.
The science behind Seraphim was originally developed for the US Strategic Defence Initiative and uses magnetic forces to hurl projectiles at 20 times the speed of sound, providing researchers with an interesting challenge: moderating the force of propulsion.
The motor generates vertical forces in addition to the horizontal propulsion forces and thus is considered a form of ‘maglev’ but the completed vehicle probably will rely on wheels, which are far cheaper, for support.
‘The main limitation to high-speed trains is air resistance, not rolling friction. So why add all the complexity needed for levitation? The TGV train in France has demonstrated that wheels are perfectly good at speeds up to 250 miles per hour,’ said Barry Marder, principal inventor of Sandia’s Seraphim technology.
Sandia researchers will design and test a prototype motor that can power a test vehicle at speeds up to 125 MPH.
This should permit actual transit at average speeds of 60-70 MPH, including stops, over grades of up to 8 1/2 percent even in the presence of snow and ice.
Conventional transit systems are said to be limited to grades of a few percent in good weather conditions, because the reliance on friction between steel wheels and steel rails limits the grade a conventional transit vehicle can safely climb.
Preliminary cost studies have shown that a Seraphim-powered transit system with the equivalent carrying capacity of 6-8 highway lanes could be deployed for between $12 and $22 million per mile, depending on corridor geography and construction conditions.