Permanent Magnet Remagnetizing Physics of a Variable Flux Memory Motor

The finite-element method incorporating with a hysteresis model has been used to analyze the variation characteristics of flux density of permanent magnets (PM) in the variable flux memory motor (VFMM). It accounts for the local hysteresis curves of PMs under different remagnetizing magnetomotive forces. Excellent agreement between the FEA predicted and measured phase back EMFs and air gap flux per pole has been achieved. It shows that the analysis method is suitable for evaluating the PM remagnetizing state in VFMM machines, and the remagnetization of PM is more difficult than the demagnetization, several times the full demagnetizing MMF is required in order to achieve the full remagnetization of PM.