Cogging Torque and Unbalanced Magnetic Pull Due to Simultaneous Existence of Dynamic and Static Eccentricities and Uneven Magnetization in Permanent Magnet Motors

Abstract

We mathematically investigate the cogging torque and the unbalanced magnetic pull (UMP) of permanent magnet motors caused by the simultaneous existence of dynamic and static eccentricities and uneven magnetization. We show that the harmonics of cogging torque and UMP are generated due to the dynamic and static eccentricities and the uneven magnetization, respectively. We also show that the simultaneous existence of dynamic and static eccentricities and uneven magnetization induces additional harmonics of cogging torque and UMP. We investigate the relative amplitudes of the harmonics of cogging toque and UMP generated by the eccentricities. The mathematical investigations are verified via numerical simulation.