ABSTRACT
This chapter discusses a variety of three- or two-phase linear permanent magnet (PM) motors that contain multi-pole nonoverlapping coils and are characterized by the smaller copper weight per Newton of thrust and thus smaller copper losses. It deals with the so-called Sawyer linear motor, which is basically a two-phase PM primary and variable reluctance secondary topology. To reduce the machine inductance and allow larger airgap with acceptable thrust density, the PMs may be placed on the surface; to reduce the PM flux, fringing flux barriers may be created into the longitudinal laminations by insulation spacers. Transverse-flux linear PM reluctance motors have been developed as counterparts of transverse flux permanent magnet synchronous motors. The transverse flux linear permanent magnet reluctance machine may be applied even for large travel, mainly for propulsion, while levitation has to be complemented by dc controlled coils on board.
