A Novel Linear Stator-PM Vernier Machine With Spoke-Type Magnets

Linear-machine-based direct-drive systems are attracting extensive attention for many industrial applications including wave energy conversion and railway traction. By using a linear machine, the complexity of linear motion systems is considerably reduced due to the elimination of the rotary to linear conversion mechanism. In this paper, a novel linear stator spoke-type permanent magnet (PM) vernier (LSSPMV) machine is presented in which the surface-mounted radial magnets used in conventional linear stator-PM vernier machines are replaced by spoke-type magnets that are magnetized parallel to the direction of motion. The proposed machine adopts a non-magnetic space between PMs and stator pole shoes decreasing the leakage flux and leading to higher flux linkage of armature winding. After designing the proposed LSSPMV machine and comparing it with its existing counterpart, the finite-element method results reveal that the thrust force density and the efficiency of the proposed machine are higher than that of the existing one as a result of utilizing spoke-type PMs.