An improved method for predicting iron losses in brushless permanent magnet DC drives

A procedure has been developed to predict the stator iron loss of a brushless DC motor with due account of the operating condition of the drive system. Finite-element analysis is used to obtain a series of instantaneous magnetostatic field distributions within a motor, for which the instantaneous currents are derived from a dynamic simulation of the drive system. Analysis of the temporal and spatial variation of the flux density distribution then enables localized iron loss densities to be determined. It is shown that the iron loss changes markedly with the operating condition