Impact of a Bonded-Magnet Adoption on a Specific Fractional Motor Power and Efficiency

Abstract

The problem of evaluating the impact on the efficiency consequent to the adoption of bonded magnets in substitution of ferrites in small permanent-magnet machines is faced. That is necessary for the development of the main object of this paper: The evaluation of the obtainable performances of a specific brushless dc motor fractional motor through simple substitution of bonded magnets proposed by the authors to the ferrite magnets used up to now. The final aim is to make clear the practical adoptability of the proposal. 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 satisfactory impact on the efficiency and the improvement of the output power of the motor with bonded magnets let possible to consider the analyzed solution as realistically adoptable.

Hybrid magnetic composite (HMC) materials for sensor applications

“…They can also be made in complex forms using injection or compression molding technologies [9]. NdFeB bonded magnets have better performance [11], but are more expensive than ferrites, while they are often a good alternative to NdFeB sintered magnets. Recently, SMC materials [12] have been sometimes adopted to replace traditional soft magnetic materials [13].…”

New Soft Magnetic Composites for electromagnetic applications with improved mechanical properties

“…available on the market is proposed by using common iron powders mixed together with organic resins: it's important to note that I.I:P.C taken as the reference is in practice the only material adopted for the applications; that justifies the choice to compare the SMC described in the paper with only one alternative product. In previous activities the Authors have experienced the adoption of resins to realize bonded magnets [14][15][16] and are now proposing the same resins to produce SMC.…”