Characteristic Analysis and Experiment of Surface-Mounted Type Variable-Flux Machines Considering Magnetization/Demagnetization Based on Electromagnetic Transfer Relations

This paper presents the characteristic analysis and experiment of surface-mounted type variable-flux permanent-magnet machines considering magnetization and demagnetization based on electromagnetic transfer relations. For this purpose, we derive the analytical solutions for the magnetic fields generated by the magnetization level of AlNiCo magnets and currents on the basis of the transfer relations in terms of a 2-D polar coordinate system. The magnetization levels of the AlNiCo magnets are determined by the magnetic fields generated by the armature reaction field. A 2-D permeance function is also introduced to consider slotting effects. The analytical results of the magnetic field are validated extensively with finite-element (FE) analyses. On the basis of these solutions, the induced voltage is also determined analytically. Finally, the predictions are compared with FE analyses and measured data to confirm the validity of the analysis methods presented in this paper.