Novel High-Order-Harmonic Toroidal Winding Design Approach for Double-Sided Vernier Reluctance Linear Machine

The double-sided dc Vernier reluctance linear machine (DS-DC-VRLM) is very suitable for long-stroke industrial processing applications, taking advantage of its magnet-free design, eliminated magnetic pull, and high dynamic response. However, its low thrust force density due to the poor excitation ability of dc windings has been a long-existing bottleneck. Aiming to boost the output thrust force of the DS-DC-VRLM, a novel high-order harmonic nonoverlapped toroidal winding design is proposed. The key is that the proposed armature winding makes full use of working harmonics modulated from both fundamental order and third-order harmonics generated by dc excitations, contributing to an enhanced winding factor. Based on the finite-element analysis (FEA), with the proposed winding design approach, DS-DC-VRLM could achieve 2.26 times higher thrust force than those with conventional concentrated winding under the same copper loss. In this article, a new winding arrangement of DS-DC-VRLM and its operation principle are introduced, along with some design considerations for it, such as slot/pole combinations, dc/ac current distributions, and extra end teeth dimensions for performance improvement. Finally, the performances of this proposed machine are evaluated by prototype experiments to verify the correctness of FEA simulation results.