Keywords
Electro-dynamic Suspension (EDS), Urban MagLev, Linear Synchronous Motor (LSM), Permanent
Magnet (PM), Pulse Width Modulation (PWM)
Abstract
A new concept in Urban Maglev transportation design is in the testing phase. The vehicle uses
permanent magnets (PM) for both the electro-dynamic suspension (EDS) and linear synchronous
motor (LSM) propulsion. Because of the 3D coupled non-linear velocity-dependent magnetic
levitation, the LSM must provide stabilizing forces to the vehicle. To do this, Vector Control is used
to modulate the inverter voltage, frequency and angle. The inverter angle is adjusted to maintain
vertical stability. The controls architecture was developed and tested in a 2D simulation and verified
in a 3D six dof dynamic model of the vehicle and guideway; the same magnetic levitation and LSM
propulsion algorithms were used in both with the 2D simulation model providing the common control
system. Control programming was implemented in C-code, which talks to the inverter pulse width
modulation (PWM) card via an intermediate control box. The 2D simulation architecture provided
the basis for implementing the control software design. Results from preliminary testing are
discussed.
1 Background
The Urban MagLev system (low speed vehicles for inner-city service) now under development at
General Atomics relies on an attraction assisted EDS for levitation and a LSM for propulsion. Both
the on-board levitation and propulsion magnets are made from high-field NdFeB. This presents a
challenge to the control system designer in that all six degrees of freedom (dof) are magnetically and
dynamically coupled and are also coupled to the LSM propulsion. At stake is not only the basic
operation of a vehicle but, because it is directed toward public transportation, the ride quality is of
paramount importance [1].
The GA Urban MagLev uses simplified algorithms developed from 3D magnetic models (OPERA by
Vector Fields) of the geometry in order to describe the forces and Simulink/Mathworks, and MSC
Nastran Motion [2] to model the 2D and 3D dynamic operation, respectively. This paper describes
the approach taken and includes a sample of the test vehicle simulation results. Included are results
from static tests run in February 2004; dynamic operation started in September 2004 and is in
progress at this time.
2 System Design
A description of the Urban Maglev is essential in understanding the controls design. A brief summary
is presented, and a more complete description can be found in reference [3] and [4].
2.1 Full-Scale Commercial Vehicle and Guideway
Although the GA Urban Maglev is still in the prototype testing stage, a first deployment is in the
planning stages at California University of Pennyslvania. The key feature of the attraction-assisted
EDS is the use of PMs for both levitation and propulsion. The system is driverless, lending to central
control. Vehicles may be operated singly or in trains. The guideway is elevated leaving full access to
the space beneath for cross-traffic. Power systems are distributed along the wayside at intervals
appropriate for block-switching, which keeps the LSM power demands to a minimum. A 2 minute
headway ensures that the LSM duty factor is low with allowance made at stations for higher starting
power demands. Figure 1 is an artist’s concept of one fully deployed vehicle.
The levitation and propulsion components are located on either side of the guideway and are
mechanically interlocked (Figure 2) with the LSMs directly above and in line with the levitation PM
Halbach arrays and ladder track. Table 1 provides a summary of the key parameters for the fully
deployed Urban MagLev system and test vehicle.

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