Experimental and Analytical Study of Surface-Mounted Type Variable Flux Permanent Magnet Motor Considering Controllable Magnet Properties

A variable flux permanent magnet motor (VFPMM) alters its characteristics at low and high-speeds by changing the magnetic flux of a variable magnet. In this paper, a motor capable of varying its magnetic flux based on the slot/pole structure is proposed. In addition, the variation characteristics of flux density and field intensity of a variable magnet in the VFPMM under magnetization/demagnetization conditions are analyzed using the finite element method (FEM) and experimentation. A prototype was tested for the magnetization/demagnetization characteristics, and it was confirmed that the value of the measured back EMF was nearly identical to the corresponding values obtained by an FEM analysis. Finally, the characteristics of the VFPMM for each magnetization/ demagnetization state were evaluated at both low- and high-speed ranges. To verify the effect of variable flux, experimental results are also presented.