New methods for reducing the cogging torque and torque ripples of PMSM

In this paper, two novel solutions for reducing the pulsating torque components of permanent magnet machines are presented and discussed. To reduce the cogging torque of PM machines, a new stator design with right- and left shifted slot openings along the circumferential direction is considered. The second solution reduces the torque ripple using a multistage rotor design with unsymmetrical flux-barriers. To prove the efficiency of these methods, the both techniques are applied during the design and optimization of two different PM machines for steering and also for traction applications. Simulation results show that, for the steering motor, a cogging torque lower than 70mNm is achieved using the new stator design, however, the torque ripple for the traction motor is reduced under 3,8% of load torque with the proposed new rotor.