Analysis of an IPM Machine with Grain Boundary Diffusion Processed Magnets

Grain boundary diffusion processed magnets provide advantages when applied in permanent magnet machines subject to high load and high temperature operating scenarios by preventing or reducing the onset of demagnetization. To investigate how grain boundary magnets affect the performance of interior permanent magnet (IPM) machines, one of the challenges is to model the magnet with grain boundary characteristics, in this case by assigning different material properties to individual magnet pieces within a discretised magnet pole. In this paper, scripts using commercial magnetic simulation software have been created to automatically generate the grain boundary magnets and define the material properties accordingly. Then, the performance of an IPM machine having a delta-shape rotor topology was analysed with conventional and grain boundary magnets and results were compared. Further, demagnetization of the magnets was analysed to verify the advantage of grain boundary magnets, illustrating that IPM machines with grain boundary magnets can realize torque and maintain efficiency at high loads while being less prone to demagnetization.