Investigation of Novel Partitioned-Primary Hybrid-Excited Flux-Switching Linear Machines

The novel partitioned-primary hybrid-excited flux-switching linear machines (PP-HEFSLMs) with unaligned and aligned structures are proposed, which exhibit advantages of direct-driven, wide speed operation, robust secondary, etc. Unlike conventional hybrid-excited topologies, the proposed PP-HEFSLMs accommodate armature and excitation windings on two separated parts of the partitioned primary, which solves the problem of crowded primary; hence, both flux-adjusting ratio and thrust force density are effectively improved. The topology and operation principle of the two PP-HEFSLMs are introduced in detail first. Based on finite-element method (FEM) analysis, major geometric parameters are investigated and optimized then. For the optimized structures, the electromagnetic performances, i.e., thrust force characteristics, demagnetization, flux-regulation capability, and inductances are calculated and further compared. The results manifest both structures show a satisfactory flux-adjusting ratio particularly for an aligned structure and good fault-tolerant capability due to tiny mutual inductances between phases. Although the thrust density of the aligned structure is relatively low compared with its unaligned counterpart, it can be taken as a mechanical flux-weakening method by aligning permanent magnets with armature teeth. Finally, three-dimensional FEM analysis is performed to validate the two-dimensional FEM predicted results.