Impact of bonded magnets adoption on fractional machines efficiency

The problem of evaluating the impact on the efficiency consequent to the adoption of bonded magnets in substitution of ferrites in small PM machines is faced. Several prototypes produced in the Authors´ laboratories have been tested and a long experimental activity has been carried on. In particular the focus of the work has been the identification and separation of the iron losses, both hysteresis and eddy currents, from the contribution of the bearings. The corresponding torques have been calculated and the energetic behaviors of the original machine with ferrites and the prototypes with phenolic bonded magnets have been analyzed. The positive impact on the efficiency of the machine with bonded magnets let possible to consider the analyzed solution as realistically adoptable.