ABSTRACT
Linear electric motors can drive a linear motion load without intermediate gears, screws, or crank shafts. A linear synchronous motor (LSM) is a linear motor in which the mechanical motion is in synchronism with the magnetic field, i.e., the mechanical speed is the same as the speed of the traveling magnetic field. The thrust (propulsion force) can be generated as an action of
• traveling magnetic field produced by a polyphase winding and an array of magnetic poles N, S,...,N, S or a variable reluctance ferromagnetic rail (LSMs with a.c. armature windings);
• magnetic field produced by electronically switched d.c. windings and an array of magnetic poles N, S,...,N, S or variable reluctance ferromagnetic rail (linear stepping or switched reluctance motors).
