Evaluation of an IPMSM Featuring a Rotor Core Directly Injection-Molded with Sm-Fe-N Bonded Magnets

This paper presents an evaluation of the characteristics of an interior permanent magnet synchronous motor (IPMSM) with Sm-Fe-N bonded magnets directly injection molded into the rotor core. Finite element method (FEM) calculations confirmed that the proposed IPMSM achieves torque characteristics that are approximately 93% of those of an IPMSM using Nd-Fe-B sintered magnets. A prototype rotor was then fabricated by injection molding Sm-Fe-N bonded magnets into the rotor core, and the motor characteristics were evaluated through actual measurements. The back EMF of the prototype motor was found to be in good agreement with the FEM calculations. Furthermore, measurements of the current phase angle versus torque characteristics of the prototype motor showed that the measured torque values closely matched the calculated values, demonstrating that the motor was fabricated as designed and confirming the validity of the proposed motor.