Reduction of torque ripple in double-layered IPMSM for automotive applications by rotor structure modification

Interior permanent magnet synchronous motors (IPMSMs) are currently widely utilized as traction motors. The objective of this study is to reduce the torque ripples in advanced IPMSMs, which cause vibrations and noise, by modifying the rotor structure. First, holes were drilled in the rotor of a double-layered IPMSM, which the authors previously proposed, and their influence on torque ripple was evaluated. Then, dents were formed in the surface of the modified IPMSM rotor, and their effect on torque ripple was evaluated. The torque ripples of the modified IPMSMs are lower than those of the reference model under maximum torque per ampere control and in other current phase angle regions. In addition, at low current, the proposed models reduced the torque ripple from that of the reference model over the entire current phase angle region.