Comparison Of Two Interior Permanent-Magnet Motors With Improved Fault-Tolerance

Interior permanent-magnet (IPM) motors are widely used in electric vehicles (EVs) for their high torque density, efficiency and extended flux weakening region. The aim of this paper is to compare two fault-tolerant IPM motors, in which fault-tolerant teeth (FTT) are adopted in both motors to offer fault tolerance. The first motor is spoke-type, and the PMs of the second one are embedded in the rotor with V-shape. For a fair comparison, the two motors are designed at the same phase current, current density, and dimensions including the stator outer diameter and stack length. The simulation models are built through two actual motor designs. The results show that the spoke-type motor has more trapezoidal back-EMF hence is more suitable for brushless DC (BLDC) operation, offering the advantages of low PMs and manufactory cost. By contrast, it suffers from the disadvantage such as high cogging torque and torque ripple as compared with the other one.