Cylindrical linear stepper motor

The subject of this paper is a novel form of linear stepper motor based purely on variable-reluctance principle, for applications requiring controlled low-speed linear motion. The motor to some extent represents the linear counterpart of the rotary variable-reluctance stepper motor and it is distinguished by the simplicity of construction, arising from its cylindrical form, which form the mechanical point of view benefits from convenience of manufacturing, assembly and extension. The main features of its magnetic configuration are: (i) each phase set forms an independent magnetic circuit and (ii) each phase winding consists of a single coil which is surrounded by a magnetic core. The power electronic switching circuits and control strategies used in the rotary doubly-salient variable-reluctance counterpart (both the stepper and switched reluctance motor type) can also be used here. A high ratio of `static thrust/mass´ has been obtained with an experimental prototype, which indicates a potential of this type of linear motor