Torque Performance Comparison Between a Ferrite Magnet Vernier Motor and an Industrial Interior Permanent Magnet Machine

This paper proposes a low-speed dual-stator spoke-type vernier permanent magnet motor (DSSVPMM) using ferrite permanent magnets (PMs). The machine is designed and verified by finite element (FE) analysis. The final design is compared against a commercial industrial interior permanent magnet machine (IPMM) using rare earth PMs and a single air gap vernier spoke-type PM machine. The final design demonstrates higher torque density, lower torque ripple, and higher efficiency than those of the IPMM and the single air gap vernier spoke-type PM machine. A PM demagnetization analysis is provided for different fault currents and temperatures. The analysis concludes that the ferrite PMs are able to withstand the fault current without evidence of severe irreversible demagnetization. The proposed design also shows balanced net radial force.