ORGANIZATION : IcAUMS 2018
JOURNAL :
YEAR : 2018.06
VOL :
PAGE :
Interior permanent magnet synchronous motor (IPMSM) is mainly used in industry requiring high output and high
efficiency of the machines such as electrical vehicle (EV) traction motors. Torque of motors is produced by the
interaction of magnetic field distribution that both stator and rotor generated. In the components that the interaction
of the magnetic field distributions produces, average torque contributes to the efficiency of the motor and torque
ripple influences to the noise and vibration of motors.
In many of conventional studies, applying notch or eccentricity is adopted to reduce torque ripple of IPMSM as the
methods can vary the magnetic field distribution. No matter how the introduced methods can reduce the torque ripple,
they also reduce the average torque and can be vulnerable to manufacturing tolerance which mainly arises in air gap.
In this paper, an asymmetric rotor shape (ARS) is adopted to vary the magnetic field distribution and thus reduce the
torque ripple. Compared to the methods dealt with in many conventional studies, the ARS can be suitable solution as
only the magnet position is changed while the air gap length and the magnet shape are constant. In addition, the
average torque value remains when the ARS is applied. This means that the torque ripple can be reduced while the
average value and the influence of manufacturing tolerance in the air gap remain.
The average torque and torque ripple according to applying or not applying the ARS are compared using nonlinear
finite element analysis (FEA) in this paper. The original and the ARS model are compared and they have the same
configuration of the stator diameter, rotor diameter, and the air gap length under the same input current condition.
As shown in Fig.2 and 3, varying the magnetic field distribution using ARS produces torque having less torque ripple.