Analysis of a Novel Double-Stator and Dual-PM Toroidal-Winding Linear Vernier Machine

Aiming at the problem of low thrust density and large thrust ripple of conventional permanent magnet linear machine, this paper proposes a novel structure of double-stator and dual-PM toroidal-winding linear vernier machine (LVM) with high thrust density and low thrust ripple. The novelty of the proposed machine is adopted double-sided topology, toroidal-winding and permanent magnets (PMs) installed both on the stator side and the mover split teeth to improve thrust density. To emphasize the specificity of proposed dual-PM LVM in aspect of electromagnetic performance, three kinds of conventional LVMs with different topologies are compared with proposed machine by analyzing the air-gap flux density, inductance, no-load EMF, thrust, overload capability and power factor of the machines. The average thrust is increased by 11.5% under rated current, and the thrust ripple is decreased from 22.1 to 2.68% by optimizing the key parameters of the proposed structure. The harmonics contribution of EMF and thrust are discussed by semi-analytical method. The results of the semi-analytical method are in good agreement with the finite element method, which verifies the correctness of the semi-analytical method and proves that the proposed machine has good performance characteristics.