Design Optimization and Performance Evaluation of a Novel Linear-Rotary Motor with Moving Coils

In order to reduce the volume and improve the torque/thrust density of linear rotary motor (LRM), a novel structure LRM with moving coils is proposed, which has only one set of stator, rotor, mover and permanent magnet (PM) units. The axially magnetized PMs are arranged alternately in the rotor along the axial direction, which are the excitation source of rotary, linear and spiral motions at the same time. The distance of linear motion is equal to the difference between the stator axial length and mover axial length. Since the amplitude ripple of air gap flux density of rotary unit is large and the amplitude regions of the air gap flux density of the rotary units are asymmetry, 3-D analytical method is adopted to conduct the design optimization with different iterative precisions by building equivalent magnetic circuit model based on lumped parameters. The prototype is fabricated and the electromagnetic characteristics of the motor are verified by experiment tests. Compared with the traditional LRM, the proposed motor has higher torque/thrust density and smaller volume.