The development of high energy magnets and their association with static converters allowed the apparition of novel electronically commuted synchronous machines with permanent magnet. This method of excitation is beneficial for machines intended to work at high rotation rates. The existence of asynchronous harmonic fields in the supply delivered by the converter produces induced currents in conductive parts of the rotor even in steady state, leading to supplementary losses and temperature rising. Eddy currents were taken into account during the functioning analysis of the static converter – machine set system and their influence is not only responsible of additional losses but they also modify behaviours of both machine and converter. Results obtained from numerical or analytical models are shown for various prototypes. Thus the study of influence of geometrical dimensions and specificities of areas where eddy currents circulate led to conclusions relative to the influence of these parameters.