Study on High Torque IPMSM Using Sm-Fe-N Bonded Magnet

Abstract

  Permanent magnet motors use powerful neodymium sintered magnets, which contain dysprosium (Dy), a heavy rare earth, to improve the coercive force in general.We have been studying heavy rare earth-free motors using bonded magnets. In this paper, the torque characteristics of a motor using Dy-free samarium-iron-nitrogen (Sm-Fe-N) bonded magnets were calculated using the finite element method, aiming for torque characteristics comparable to those of a motor using neodymium sintered magnets. This study shows that a motor using Sm-Fe-N bonded magnets can output torque close to that of a motor using neodymium sintered magnets by changing the magnet arrangement of the rotor from a V-shape to a U-shape to increase the magnet surface area and to eliminate leakage flux at the flux barrier.