Improved Primary/Secondary Pole Number Combinations for Dual-Armature Linear Switched Flux Permanent Magnet Machines

Due to additional armature windings on the secondary, dual-armature linear switched flux permanent magnet machines (DALSFPMMs) exhibit higher force densities than conventional LSFPMMs. Nevertheless, the existing DALSFPMMs suffer from larger secondary phase numbers because of the prime secondary pole numbers. This article proposes more optional primary/secondary pole number combinations with fewer phase numbers for DALSFPMMs. The machine topology is introduced first, followed by the analysis of phase numbers, which indicates the DALSFPMMs with 8/9 primary/secondary poles (8p/9s) and 9p/8s have fewer phase numbers and need fewer power electronic devices. Then, the operation principle of DALSFPMM is analyzed from the perspective of air-gap field. After that, the electromagnetic performances of four DALSFPMMs with 8p/9s, 9p/8s, 6p/7s, and 6p/5s are investigated by 2-D finite element method, showing the 8p/9s and 9p/8s machines have higher average thrust forces, lower thrust force ripples, and higher thrust force to permanent magnet (PM) volume ratios than the 6p/7s and 6p/5s counterparts. Finally, a prototype machine is manufactured for the experimental validation.