Study of the Total Demagnetization Fault of an AFPM Wind Generator

This article investigates the total demagnetization fault in Axial Flux Permanent Magnet (AFPM) synchronous generator, suitable for wind power applications, using the three-dimensional Finite Element Method (3D-FEM). The machine, in which the demagnetization diagnosis has been investigated, consists of one coreless stator with concentrating winding, embed in resin and two rotors. In the current study, faulty cases of different number and relative position of total demagnetized magnets are studied. Finally, simulation results are compared to experimental results for validation. The stator current spectrum is studied as fault identification mean and it is shown that the fault signatures depend on the number of total demagnetized magnets, the relative position of the magnets on the rotor and the stator winding topology. In addition, there is an investigation of the partial demagnetization fault for comparison purposes. Moreover, analytical expressions for the magnetic flux density in the healthy case and in every faulty case are exported. These novel expressions, related to every demagnetized case, are presented for the first time in the literature.