Investigation of a novel double armature brushless DC linear motor

A novel homopolar DC linear motor with a novel topology is proposed. It employs a movable set of NdFeB-type magnets as source of excitation. The design of the machine was optimised to achieve a large force to volume ratio. Although the motor is slotless, it can be used as a linear stepping motor. The model of the motor and its optimisation procedure were developed on the initial assumption that the magnetic circuit is linear. To analyse the magnetic flux distribution throughout the volume of the motor, a 3D electromagnetic finite element analysis of the motor was performed. The assembled prototype had its flux density at specific points and the static force along the travel length measured. The assessment of the analytical, numeric and measured values shows a quite good correlation among them. The results as well as the optimisation procedure are presented and discussed in this paper.