Electromagnetical design of surface mounted P.M. axial-flux synchronous motors

Although permanent-magnet synchronous machine design is well known and has been treated in technical literature, the non-linearity introduced by the saturation of the iron laminations has not been considered. This fact makes uncertain the calculation of the stator-rotor mutual reactance (X_m) and therefore the no-load voltage (E_f) is also undefined. Both inexactitudes have incidence on the power calculations. Especially sensitive is the determination of the power losses in the design procedure, because it is necessary to compare solutions with efficiencies over 95 per cent.. In this paper a straightforward calculation procedure of the flux and current densities for a given machine size, taking into consideration “exactly” any degree of saturation for a given current field oriented control angle is presented. The results obtained with this procedure match well with those obtained with finite element programs and with the values measured in an axial flux synchronous motor laboratory prototype.