Quantitative Analysis of Asymmetric Flux Reversal Permanent Magnet Linear Machine for Long Excursion Application

This article proposes two kinds of asymmetric flux reversal permanent magnet linear machine (AFR-PMLM) for long excursion application. By utilizing asymmetric permanent magnet excitation, the AFR-PMLM can effectively generate and fully exploit the second-order harmonic magnetomotive force (MMF), leading to a significant enhancement in thrust force density. First, the machine topology and operation principle are introduced. Then, the thrust force generation mechanism under multi MMFs is analytically calculated based on an improved MMF-permeance model, and further verified by finite element analysis. Various electromagnetic performances, including open-circuit characteristics, thrust force performances, and power factor, are comparatively studied. It shows that the proposed AFR-PMLM with consequent pole structure can provide 40.1% higher average force than conventional FR-PMLM under rated condition. In addition, it consumes only about 39.5% of the PMs volume while providing approximately 90.4% of the thrust force compared with switched flux PMLM. More importantly, the AFR-PMLM consumes only 1/80 PMs volume while achieving 75.0% of the thrust force density compared with conventional PMLM for a long excursion with 10 m. Finally, two prototypes of AFR-PMLM are manufactured for experimental validation.