Eddy-current losses of surface-mounted permanent-magnet motors

The paper presents an analytical method for estimating the eddy-current losses of surface-mounted permanent-magnet motors under load conditions. These losses are related to a fictious voltage induced in a one-turn coil wound around a stator tooth. A simple way to calculate part of the load currents for this voltage is described. It is shown that only the windings found in adjacent slots to the stator i.ooth considered contribute to it. Waveforms of this fictious voltage, including the load current effects, are shown. They illustrate the increase of eddycurrent losses with motor load, particularly in conditions of advanced commutation.