ABSTRACT
Linear electric motors belong to the group of special electrical machines that convert electrical energy directly into mechanical energy of translatory motion. Linear electric motors can drive a linear-motion load without intermediate gears, screws, or crank shafts. The application of direct current (DC) linear motor is marginal. The most popular are permanent magnet (PM) linear synchronous motors (LSMs) and linear induction motors (LIMs), which are manufactured commercially in several countries and are finding many applications. The part producing the traveling magnetic field is called the armature or forcer. The part that provides the DC magnetic flux or variable reluctance is called the field excitation system or salient-pole rail, reaction rail, or variable reluctance platen. In surface arrangement of PMs, the yoke (back iron) of the reaction rail is ferromagnetic, and PMs are magnetized in the normal direction. Buried PMs are magnetized in the direction of the traveling magnetic field, and the yoke is nonferromagnetic, for example, made of aluminum.
