Design and Analysis of Hybrid-Excited Flux Modulated Linear Machines With Zero-Sequence Current Excitation

This article investigates a hybrid-excited flux modulated linear machine (HEFMLM) with zero-sequence current excitation. With the adoption of integrated open winding, zero-sequence current can be utilized to provide the dc excitation and further improve the thrust force density. First, the machine topology, drive circuit, and operation principle are described. Then, the magnetomotive force (MMF)-permeance model is built to analytically calculate the air-gap hybrid-excited field harmonics and further verified by finite element (FE) analysis. Moreover, the electromagnetic performances including open circuit characteristics, flux regulation capability, thrust force characteristics, and demagnetization risk are comparatively studied. Due to the improved exciting field and armature MMFs with integrated winding, the thrust force capability can be significantly enhanced by 22.6% on the premise of rated copper loss. Besides, the proposed HEFMLM exhibits high thrust force density compared with the other three types of HEFMLM, benefitting from a high pole-pair number of permanent magnets (PMs) along with a more obvious magnetic gearing effect. Finally, a prototype of the HEFMLM is carried out for experimental validation.