Linear Motor Powered Transportation

It has been a pleasure to assemble these outstanding papers on Linear Motor Powered Transportation: Past, Present, and Future. This topic takes on increasing importance as we seek ways to make transport systems faster, more efficient, and more affordable. We were able to recruit outstanding engineers and managers to devote many hours to writing these papers, which come from six countries on three continents. The authors are from industry and academia, and are all experts in their field. We encouraged the authors to describe current supporting technology and linear motor systems, past history, and projections for the future. These papers have broad coverage of important ideas and can be understood by people who are not experts in the field. Many of the papers include substantial bibliographies that can be used to further explore the topics. There are many types of linear motors, but most of those discussed in these papers are the short primary linear induction motor (LIM) and the long primary linear synchronous motor (LSM). They are similar to their rotary counterparts, but the linear versions represent a more complex design challenge. Some papers use the term stator for the part of the motor that is excited, but since this is sometimes on the moving vehicle, it seems better to use the transformer terminology Bprimary.[ There is one paper on the long primary LIM. It is possible to build a short primary LSM, but there is no paper on this topic. Unless otherwise stated, LIM refers to transport systems in which power is transmitted to the vehicle and the guideway is passive, while LSM refers to systems in which the propulsion power is supplied to windings on the guideway and no propulsion power is transmitted to the vehicle. One important application of linear motors is the propulsion of vehicles that are suspended by magnetic fields. In 1968, Coffey coined the term Bmaglev[ to refer to a Btransport system using magnetic suspension and propulsion.[ There are two common types of maglev: electromagnetic suspension (EMS), in which the vehicle is supported by attractive forces between magnets on the vehicle and a ferromagnetic structure on the guideway, and electrodynamic suspension (EDS), in which magnets on the vehicle move in the vicinity of conducting material and currents induced in the conductors react with the vehicle fields to provide lift. A key part of maglev design is integration of a linear motor propulsion system with the suspension. Either LIM or LSM propulsion can be used with EMS and This Special Issue on Linear-Motor Powered Transportation covers both supporting technologies and innovative transport systems in various parts of the World, as this technology moves from the lab to commercial operations.