Abstract：In this paper, the magnetic field distributions of a variable flux memory motor (VFMM) with different rotor permanent magnet (PM) cross section shapes under no-load and d-axis demagnetization are analyzed by finite element method. A detailed description on the changes of bypass flux and zero flux density area in the rotor is given. The influence of PM cross section shape on the field-control parameters of VFMM, such as the maximum air gap flux per pole, the air gap flux density, the maximum demagnetizing ampere-turns, and the flux density on the centerline of PM are numerically investigated. It is found that the utilization ratio of PM can be considerably improved by choosing a reasonable PM section shape. When the PM cross section shape coefficient is less than 0.6, the demagnetization effect of PM can be guaranteed easily. When the PM shape approaches rectangular, to ensure the validity of PM demagnetization, the working point of PM should be demagnetized below the knee point. The conclusions obtained by this paper will be helpful to the design and control of VFMM.
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2009, Vol. 24 
