Improved V‐shaped interior permanent magnet rotor topology with inward‐extended bridges for reduced torque ripple.

Interior permanent magnet synchronous machines (IPMSMs) with V‐shaped permanent magnet (PM) rotors are widely used as traction motors in electric vehicles because of their high torque density and high efficiency. However, the V‐shape IPMSMs have the disadvantages of inevitable torque ripple due to the non‐sinusoidal air‐gap flux density distribution and the utilisation of the reluctance torque. In this study, with the aim of improving the torque ripple characteristics, a modified V‐shaped IPMSM rotor configuration with bridges extended inwards towards the pole centre is proposed to generate a more sinusoidal air‐gap flux density waveform. The proposed topology, referred to as 'Type C' within this study, is compared with baseline rotor configuration references, namely 'Type A' which is a conventional V‐shaped PM rotor, as well as 'Type B' which is a related configuration with a mechanically non‐uniform air gap. The analysis results show that the rotor 'Type C' exhibits significant advantages in terms of reducing cogging torque, torque ripple and radial force, without incurring additional air‐gap friction losses. Finally, a prototype of the IPMSM with the proposed rotor configuration is manufactured and tested, verifying the predicted benefits experimentally. [ABSTRACT FROM AUTHOR]