The monorail is powered by a linear induction motor (LIM). LIMs have
been around for some time. The monorails at Euro Disney are powered by
LIMs, as is the Vancouver rapid transit system. The senatorial transit
system in Washington DC, and many roller coasters and baggage handling
systems, are all powered by LIMs. LIMs were used to propel test trains at
speeds up to 250 mph at the Transportation Technology Center, Colorado, in
The LIM used on the monorail is a new and improved version, Seraphim
(SEgmented RAil PHased Induction Motor), developed by Sandia National Laboratories.
The Seraphim motor was originally designed to launch satellites into
orbit. It can accelerate a one ton satellite up a 0.6 mile-long track with
a 30% upward grade to a speed of 14,000 mph, sufficient to launch the
satellite into low earth orbit.
How a Seraphim LIM Works
Mount a permanent magnet to the underside of a vehicle. Now slide
another magnet along the track and if the second magnet is oriented
correctly, the magnets will repel, causing the vehicle to move.
Instead of sliding a magnet along the track, put in a whole series of
magnets. Change the magnet on the underside of the vehicle into an
electromagnet so that you can turn it on and off. Now when the
electromagnet is in the correct position relative to a magnet on the track
(just beyond its center), turn it on so that the magnets repel and the
vehicle is pushed along. Turn the electromagnet off before it gets too
close to the next magnet (or it will brake the vehicle). Let the vehicle
run on just past the next magnet, and then pulse the electromagnet again
so that the vehicle continues moving forward. Continue this process. To
brake the vehicle, pulse the electromagnet just before it reaches a magnet
on the track.
Instead of using permanent magnets in the track, use a segmented
aluminum rail (a ladder-like structure) which will act as a series of
electromagnets, but do not supply any power to the rail. Now when the
electromagnet on the vehicle is in the correct position relative to a
segment on the track, turn it on. It will induce surface currents in the
segment, generating a magnetic field, so that the electromagnet on the
vehicle will be repelled and the vehicle will move forward. Keep pulsing
the electromagnet on the vehicle every time it is in the correct position
relative to a rail segment on the track. The segmented rail along the
track is called a "reaction rail".
To go fast, mount a number of electromagnets to the underside of the
vehicle so that any one time 40% of them are in the correct position
relative to a rail segment on the track and are pushing forward smoothly.
An alternative to using onboard power is to use a power pick-up to connect
each electromagnet on the vehicle to the "third rail" which is connected
to an external power supply.
The advantages of a LIM over conventional motors and drive systems are
Because there are no moving parts, a LIM is very quiet.
Propulsion is by electromagnetic forces between the active coils on
the vehicle and the reaction rail - not through traction between the
wheels and rail. This means a monorail with a LIM can climb steep grades
and in rain, snow and ice without depending on wheel traction. The
monorail's wheels carry the vehicle weight and provide guidance, not
traction, minimizing wheel and track wear.
If the reaction rail is placed on top of the guideway beam, as is
the case with the high-speed monorail, then there is a vertical
component to the electromagnetic forces between the active coils and
reaction rail. This uplift force can be as great as 90% of the weight of
the vehicle. This magnetic lift can improve ride quality, make the
monorail even quieter, reduce friction in the suspension system (static
and rolling drag), and improve energy efficiency and acceleration.
Comparison of the Seraphim and Conventional LIMs
The Seraphim motor is a new form of LIM that generates thrust by
pulsing an alternating current through each active coil mounted on the
vehicle when it is properly positioned over the unpowered reaction rail.
The reaction rail is not continuous as is the case with conventional LIMs,
rather, it is a segmented structure. The magnetic flux from the driving
coil induces currents in the segmented reaction structure, creating forces
for propulsion or braking due to the interaction of the magnetic fluxes.
This is unlike a conventional LIM where magnetic flux is embedded in the
continuous reaction rail in order to create propulsive forces.
Since the Seraphim motor relies on the exclusion of flux from the
reaction rail, it has the following advantages over conventional LIMs for
use as a high-speed rail propulsion technology:
It permits a larger gap between the active coils on the vehicle and
the reaction rail on the guideway, up to 1", and perhaps larger, which
improves ride quality and relaxes guideway tolerances, significantly
reducing construction and maintenance costs.
Very low magnetic drag is induced in the reaction rail (assuming
proper motor control), which improves motor efficiency.
It is smaller, lighter, and more compact than a conventional LIM,
and costs significantly less to build and operate.
The efficiency of the motor increases with speed.
The power of the Seraphim motor is limited only by the power available,
the frequency of pulsing relative to the required energy input necessary
for a desired speed of operation, and by the maximum
acceleration/deceleration forces that can be comfortably accommodated by
The bottom line is:
The Seraphim motor may be the fastest motor ever developed.
At the same time, it is not complex and hence it is relatively
inexpensive to manufacture and maintain.
LLC, a wholly-owned subsidiary
of Meneren Corporation was competitively selected
by the State of Colorado to design, construct, and
operate a 170 mile high-speed monorail system that will
connect DIA (Denver International Airport), stop in the
center of the City of Denver, and proceed up the Rocky
Mountain corridor to the ski areas (including Vail), and
on to the Eagle County Airport.
MagLift Technology has been designated a
"Maglev" technology by the US Department of
Transportation. However, unlike fully levitating
Maglev systems, MagLift is substantially lighter, lower
cost, and can stay within highway right-of-ways.
Copyright (c) 1994-2015, The Meneren Corporation. All Rights