The Magplane Basic Components
The
Magway
The
magway trough has a 2.1 m radius, and is 4.5 m wide. It is divided
into three segments: a meander-shaped propulsion winding in the
center serves as the stator winding of the linear synchronous motor.
It is cast into a fiber-reinforced composite slab and flanked by two
levitation sheets consisting of 2 cm thick sheets of curved 6061-T6
aluminum alloy approximately 100 cm wide. Levitation is provided by
image currents induced in these sheets by the moving vehicle
magnets.
The
trough is supported by a compound-curved box girder made of aluminum
and supported on pylons to provide a mid-span deflection of about
4.5 mm maximum. Magways are elevated throughout. Longer spans are
reinforced with pre-cast concrete structures. The intercity magway
is banked for a design speed of 500 km/h, up to a maximum bank angle
of 20 degrees. Magway design provides for emergency stopping and
re-starting from any location in the guideway. Wherever the vehicle
is stopped, its center of gravity passively returns it to the
upright position.
Magplane
Stations
Like
a subway system, the Magplane commuting service would offer passengers
many choices of station stops. The large number of stations allows
the Magplane to distribute passenger boardings and alightings over
a large geographic area to maximize the line haul capacity of the
system and minimize the station access/egress time for passengers.
Because the Magplane service operates with single vehicles rather
than coupled rail or subway cars, commuters can bypass these off-line
stations until reaching their ultimate destination. Transfer stations
would provide passengers with high frequency service from stations
in low density markets.
Magplane
Technology provides flexibility in locating stations both during
the initial construction, or importantly, after a system has been
built. The technology enables growing urban regions to access the
Magplane system in response to rapidly changing land development
patterns.
The
Magplanes
 Magplane
vehicles resemble a mid-size jet fuselage with five across seating.
They vary in length from an 80 passenger (22 tonne) intercity
vehicle to a 250 passenger (45 tonne) intracity vehicle. Freighters
will carry priority cargo during off-peak hours.
Magplanes have no on-board power source other than emergency battery
back up. All propulsion power and on-board power is provided by the
meander windings in the magway. The vehicles carry induction coils
to pick up on-board power for housekeeping and control.
Magplane
Switching
At
each exit from the main magway there is a magswitch which can divert
any Magplane to a spur line or magport. This works on command from
the central computer by selectively opening and closing guidance
coils in the magway. The magswitch has no moving parts, works instantly,
and can switch at full cruising speed.
On-Board
Magnets
The
on-board magnets are "permanent magnets" made from
neodymium-iron-boron materials. There are arranged in sets
magnetized so as to maximize the field outside the vehicle and
minimize the field inside the passenger compartment, so-called "Halbach
Arrays."
There
are four lift pads with a total weight of 5.5 tonnes, which exert a
magnetic pressure on the aluminum under the pads of about 1
atmosphere. This is a small fraction of the local pressures under
conventional rail vehicles. They levitate the vehicle 10 cm above
the guideway surface.
The
position of the lift pads relative to the surface of the vehicle is
controlled by aircraft type hydraulic position control systems.
Changes in the position of the individual pads are used to control
the operating gap during startup and to provide damping of any small
amplitude mode oscillations in vehicle attitude necessary to assure
passenger ride quality.
The 5.5
tonnes of propulsion magnets are distributed along the underside of
the vehicle, and are also arranged in Halbach arrays.
Being
"permanent", none of the onboard magnets require power to sustain
their magnetic fields. This gives rise to a large reduction in
potential failure modes, and will be a major contributor to a high
overall safety rating for the system.
Below a
minimum levitation speed of 18 km/hr the vehicle rides on
permanently deployed rubber tires that project 3 cm from the vehicle
surface. The wheels are equipped with mechanical brakes for
emergency stopping in the event of a failure of the linear
synchronous motor braking system.
Vehicle
Dynamics
 The
Magplane is supported resiliently above the magway by a relatively
soft magnetic levitation, but also uses an active secondary
suspension. Although repulsively levitated vehicles are inherently
stable, they are also undamped and therefore capable of oscillating
in all six modes of freedom; heave, pitch, sway, yaw, roll and
thrust. The amplitude of the oscillations can impact passenger
comfort if uncontrolled. Therefore the Magplane dynamic control
system prevents such oscillations by introducing active and passive
damping.
Active
damping is provided by two independent means which supplement each
other. The primary damping system is based on mechanical control of
the lift pad position relative to the surface of the vehicle.
Control signals are derived from on-board accelerometers and
measurement of the vehicle-to-guideway gap at the four corners of
the vehicle. The pads can be extended or withdrawn by 2 cm,
producing a plus/minus 25% change in lift force. The frequency
response of the system is compatible with the 1 Hertz resonant
frequency of the vehicle suspension. The pad position damping
control is supplemented by actively controlled aerodynamic surfaces
that are more energy efficient than the pad controllers at higher
speeds. Additional roll damping is provided by the "keel effect" of
the interaction of the propulsion magnets with the edges of the
linear motor slot in the aluminum guideway.
Vehicle
motion has been simulated by means of a full six-degree-of-freedom
computer model that demonstrates that the active damping systems can
provide passenger comfort that meets standard ride quality measures.
The
Magway Power System
 The
magway is divided into power blocks of about 2 km length. Only one
Magplane occupies any power block at a given time which provides
collision protection. Each power block is energized by a wayside
power conditioning unit of 6 to 20 MVA capacity depending on local
power requirements for grade and acceleration. The linear synchronous
motor and installed power give Magplane the capability of climbing
or descending a grade of 10%, comparable to automobiles, whereas
trains are limited to about 1%.
The
wayside units are cyclo-converters (solid-state switched transformer/rectifier-inverters)
capable of supplying three-phase AC current with adjustable frequency
and phase. They can provide acceleration, synchronous propulsion,
or deceleration as required, on the basis of position information
transmitted from the vehicle, and system control information transmitted
from the central control computer.
The
Control Systems
The
on-board, the wayside and the global controllers form a safety rated
hierarchy of command.
The
on-board controller discriminates between transients (wind gusts),
magway imperfections and magway curves on the basis of a set of
inertial sensors, a set of magway proximity sensors, and a memory
of the magway alignment. It initiates remedial action by requesting
an LSM phase shift from the wayside controller, and/or a deflection
of the aerodynamic surfaces, and/or a position change of the lift
pads.
The
wayside controller manages the power conditioning unit for one power
block in cooperation with the one vehicle which occupies that block
at any given time, and in compliance with instructions from the
global controller. It maintains the required speed, acceleration
or deceleration, and adjusts the propulsion winding phase so as
to apply instantaneous vertical or longitudinal forces which are
required to damp oscillations.
The
global controller directs all Magplanes in the system and manages
the system traffic in response to status and demand. It ensures,
for example, that the traffic gap created by a vehicle exiting at
one city is moved promptly to another where a stopped vehicle is
waiting to re-enter the magway. The global controller also makes
sure, for example, that a passenger who has requested to go from
point #1 to point #2 waits no longer than fifteen minutes to be
picked up, and that passengers get non-stop service whenever possible.
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