Linear Synchronous Motor Propulsion of Small Transit Vehicles

The Linear Synchronous Motor (LSM) has been used for several high speed maglev applications but only recently have developers applied it to urban transit. MagneMotion has worked with the Federal Transit Administration (FTA), as part of their Urban Maglev Project, to develop an LSM propelled maglev transit system called M³. The top speed is only half that of the Transrapid maglev trains now operational in China but by using small vehicles with short headway and rapid acceleration it is possible to achieve outstanding performance at much lower cost. The combination of LSM technology and small vehicles is a cost effective replacement for rotary motor and Linear Induction Motor (LIM) powered trains for all transit applications, including conventional rail and monorail. LSM is the enabling technology that makes it economically and technically feasible to achieve high capacity with short vehicles and, conversely, the use of small vehicles makes LSM propulsion economically attractive. Small vehicles operating with short headway and organized in clusters can achieve high capacity without offline loading. Very precise position sensing and guideway based propulsion and control make short headways safe and affordable. This paper describes the objectives of the MagneMotion LSM development, discusses some of the design features, and presents 3 examples. The examples are based on operational speeds up to 60 m/s (134 mph), accelerations up to 0.16 g, vehicle headways down to 4 seconds, and capacities up to 12,000 passengers per hour per direction (pphpd). Examples include a 1 mile high capacity shuttle, a 4 km unidirectional loop with several stations, and a 30 km high-speed airport connector. Calculations show that an LSM propelled transit system has lower capital cost than conventional transit systems using vehicle-based electric propulsion with either rotary motors or LIMs. Vehicles are simplified, the cost of energy and maintenance is reduced and, most important, users of the transit system experience major reductions in trip times.