EMF computation with commutation phenomena effects for PM DC motor

A method for modelling the effect of commutation for a radial-field DC motor is presented to enable the analytical prediction of the oscillations of the induced EMF as well as its average value. Commutation phenomena are considered. A mathematical approach is based on the superposition of EMF induced in each coil of the armature winding. A classical model for magnetic field distribution produced by magnets is reviewed. It takes into account implicitly the iron saturation and the effect of rotor slots opening. Model forecasts are consistent with results obtained by finite element analysis as well as experimental results.