Hybrid rotor multiple magnets (HRMM) design for traction motors

line graph shows Speed-Torque Characteristics
Speed-Torque Characteristics

CMI researchers at Ames National Laboratory conducted the research for this highlight

A Hybrid Rotor Multiple Magnets (HRMM) design is proposed to reduce the use of rare earth elements in electric vehicles, while maintaining comparable performance with a commercial design.


  • Substitutes 50% of Nd-Fe-B magnet in 2010 Toyota Prius with ferrite magnet. 
  • Maintains comparable speed-torque characteristics with original Prius 2010 design. 
  • HRMM offers a higher torque/$, compared to the original design.

Significance and impact

  • Addresses potential shortages in critical rare earths. 
  • Enables sustainable vehicle electrification.

Hub Goal Addressed
Reduction of critical RE magnets usage in EV motors.


bar graph shows Peak Torque and Torque/$ Comparison
Peak Torque and Torque/$ Comparison