Design of a Novel IPMSM Bridge for Torque Ripple Reduction

The interior permanent magnet synchronous motor uses a barrier structure to block the magnetic flux circulating inside the rotor and to send the magnetic flux into the air gap. Although the airgap magnetic flux density can be increased through the barrier, there is the disadvantage of increased torque ripple. Thus, this study is conducted to determine whether the torque ripple could be reduced by changing the barrier shape. The problem here is that the torque inevitably decreases when the torque ripple is decreased. Therefore, in this study, a novel shape of the bridge is proposed in a model in which the torque ripple is reduced but the torque is not. The notch structure is applied to the bridge and is analyzed through finite-element method analysis. To intuitively express the relationship between the torque and the torque ripple, a torque efficiency factor is devised, and as a result, the torque is maintained but the torque ripple is reduced.