Research on combined pole for interior permanent-magnet machine

Owing to the advantages of high power density and salient field-weakening performance, interior permanent-magnet (IPM) machines are widely applied in electric vehicles (EVs). However, rare-earth permanent magnets can be demagnetized irreversibly because of large demagnetizing current and high temperature. Hence, this paper proposes a combined pole IPM machine which can improve the demagnetization withstand capability. The combined pole adopts hybrid NdFeB and ferrite magnets to improve the air-gap flux density, further improving the machine performances. Based on finite-element analysis (FEA), the machine performances are evaluated and compared with those of the conventional shaped pole machines.