A linear switched-flux PM machine with 9/10 primary/secondary pole number

Based on the optimal primary and secondary pole number combination selection principle of linear switched-flux PM machine (LSFPMM) with odd poles primary, a novel 9/10 primary/secondary poles LSFPMM has been developed. In order to increase the thrust force density, some major design parameters, such as secondary pole width, split ratio and primary slot width, were investigated by finite element analysis (FEA). Because of the discontinuity of the primary, there exists longitudinal end effect in LSFPMMs, which significantly affects the smoothness of thrust force. In order to decrease the thrust force ripple under on-load condition, the effective method of utilizing end auxiliary tooth was adopted and their positions were also optimized. Finally, the electromagnetic performances were calculated and compared, which could be beneficial to understand the characteristics of LSFPMM. The results demonstrate that the odd pole primary is suitable to LSFPMM and may be a good candidate for long-stroke direct linear drive application.