Linear synchronous motors for high-speed ground transportation

Modern intercity ground transportation requires such high speeds that novel means of suspension and propulsion must be developed. Wheelless trains driven by linear electric motors offer definite advantages with regard to passenger safety and comfort, reliability, efficiency, chemical and noise pollution. Projected densities of traffic may even render economical the transfer of energy from the wayside, by utilizing the mechanism of electromagnetic induction. Various realizations of linear synchronous motors, energized from either the vehicle side or the wayside, are considered, their relative merits, when compared with linear induction motors, are assessed, and the constraints which their peculiar operational and stability characteristics impose on the designer are highlighted. It is concluded that the structural complexity of the linear synchronous motor warrants an effort to make use of the same electromagnets for propulsion, suspension, and lateral guidance. Although sophisticated control systems may be needed, no basic obstacle appears to stand in the way toward the achievement of such a goal.