Torque speed characteristics of switched flux permanent magnet machines.

Purpose – The purpose of this paper is to investigate the influence of end-effect and cross-coupling on the torque-speed characteristics of switched flux permanent magnet (SFPM) machines. Design/methodology/approach – The torque-speed characteristics are predicted using two different methods. These are direct and indirect finite element methods, at different cross-coupling levels, namely, full cross-coupling on both PM flux linkage and dq-axis inductances, partial cross-coupling on the PM flux linkage only and without cross-coupling. Findings – The influence of the cross-coupling on dq-axis inductances of the studied machine is relatively small. However, it is more significant on the PM flux linkage. Therefore, the partial cross-coupling model, which is much easier and faster, exhibits almost the same accuracy as the full cross-coupling model. Furthermore, the end-effect causes a large reduction in torque-speed characteristics. However, such a reduction is more significant in the flux weakening operation region. Originality/value – This is the first time that the influence of end-effect of SFPM machines on the torque-speed characteristics, especially in flux weakening region, and on the dq-axis inductances has been investigated. [ABSTRACT FROM AUTHOR]