Research on Noninteger Pole Number for Segmental Permanent Magnet Linear Synchronous Motor

A segmental permanent magnet linear synchronous motor (S-PMLSM) with noninteger pole number, which has low detent force and high thrust, is presented in this article. For the S-PMLSM, the noninteger pole structure makes up for the defect that the conventional integer pole structure cannot suppress the third and its times harmonics in the detent force, thereby further reducing the thrust ripple rate of the motor. Special winding arrangement is adopted for noninteger pole structure, of which the winding factor is relatively high. Another advantage of the noninteger pole structure is the decoupling between the detent force and the cogging force. When designing cogging parameters and structures, it is not limited by the requirement of the detent force, which enlarges the range of cogging parameters and finally helps to improve the motor thrust. In this article, 18-slot 24-pole and 18-slot 19.2-pole S-PMLSMs, representing integer and noninteger pole structures, respectively, are selected as samples for comparative analysis. The results show that the later removes almost all detent force while giving higher thrust than the former. The simulation and experimental results validate the research theory.