Design criteria of a tubular linear IPM motor

This paper describes the design criteria of a tubular linear motor, with interior permanent magnets. The key equations for the analysis of the motor are at first derived, considering both slotted and slotless topologies. Then, these equations are rearranged with the purpose of obtaining useful hints for the motor design. Force-to-volume ratio of different motor design solutions are compared considering the effect of motor dimensions and permanent magnet materials (ferrite and NdFeB). A finite element analysis is used to validate the results obtained from the analytical model, comparing the magnetic field quantities as well as the mechanical force. Basic considerations for the design of this kind of motor are reported.