Effect of Variable Recoil Permeability on Demagnetization Characteristics of Permanent Magnet Assisted Synchronous Reluctance Motor with Bonded Magnets

Abstract

Irreversible demagnetization analysis is complicated in motors with bonded magnets that have unique B-H curves and do not exhibit distinct knee points. We have proposed a permanent magnet assisted synchronous motor (PMASynRM) with bonded magnets and examined its demagnetization characteristics by assuming the relative recoil permeability (μ_rec) as constant to simplify the analysis. However, the present recoil loop measurements of bonded magnets show that μ_rec has different characteristics depending on the magnitude of the reverse magnetic field intensity at the working point of the magnet and temperature. Therefore, this study presents a demagnetization analysis method based on these measurement results and investigates the demagnetization characteristics of a PMASynRM considering the variation in μ_rec for bonded magnets. The results of the demagnetization analysis considering the variation in μ_rec are compared with those where μ_rec is assumed to be constant. The comparison results indicate that there is no problem with assuming a constant μ_rec of 1.15 in the demagnetization analysis of a motor with bonded magnets.