Power Factor Investigation of Four Different Linear Flux-Switching Machines Used for Railway Traction Application

In this paper, four typical topologies of linear flux-switching machines (LFSMs), which are the conventional permanent magnet linear flux-switching machine (PM-LFSM), the complementary modular linear flux-switching permanent magnet machine (MPM-LFSM), the conventional linear flux-switching electrical excited machine (E-LFSM) and the complementary modular linear flux-switching electrical excited machine (ME-LFSM) with large airgap are comparatively studied from the aspect of power factor and thrust force for railway traction application. First, the structures and working principles of the four typical topologies are illustrated and discussed. Second, the power factors of the permanent magnet and electrical excited LFSMs are analyzed according to the mathematic model including the influence of the mutual inductances between d-axis and q-axis. Finally, the effects of airgap length and the width of field excitation parts on the power factor and thrust force of the four machines are investigated in detail.