Influence of rotor structures on line-start permanent magnet machines electromagnetic characteristics for pumping units application

This paper investigates the opportunity to use a proper geometry of Line start permanent-magnet synchronous motor (LSPMSM) that allows the same stator to be used for three different rotor structures, namely, typical, solid rotor and strange rotor. The air-gap flux density, back electromotive force (EMF), cogging torque, efficiency, starting performance and synchronization capability of the three machines are analyzed and compared. It is demonstrated that the typical rotor has the highest air-gap flux density, and the strange rotor has the lowest cogging torque and highest starting torque. In addition, the solid rotor has the lowest total harmonic distortion (THD), the highest efficiency, and the lowest cost. The size of PM and rotor structure are optimized to maximize the starting torque and efficiency of the solid rotor LSPMSM based on response surface method (RSM). Finally, the solid rotor LSPMSM is prototyped to verify the results of the finite element analysis.