Interior permanent magnet machines with rare earth and ferrite permanent magnets

This paper proposes a novel interior permanent magnet machine (IPMM) design in which the rotor employs U-shape magnet cavities filled with both rare earth and ferrite permanent magnets (PMs). The design aims to replace a portion of rare earth PM materials by ferrite magnets in order to minimize the material cost. The proposed design has been developed based on the Camry 2007 V-type IPMM, which serves as the baseline design in the performance comparison. The performance of the proposed design has been verified by the finite element method (FEM). The proposed design uses 20% fewer rare earth materials to achieve a 4% higher torque performance than the baseline design. The demagnetization analysis proves that the ferrite PMs in the proposed design have the same susceptibility as that of the rare earth PMs in the Camry design to the demagnetization field.