Multilayer Bonded Magnets in Surface-Mounted PM Synchronous Machines

This paper investigates the manufacturability and applicability to electrical machines of unified multilayer magnetic blocks consisting of PMs with variable magnetic force. In particular, the self-produced multilayer magnets are realized using compressed phenolic NdFeB bonded powders for the `strong' magnet layer, and hybrid composite materials for the `weak' magnet layer. Different material combinations for the self-produced permanent magnets have been experimentally investigated, and their applicability of resultant multilayer bonded magnets to electrical machines is articulated on the basis of simulations. An existing geometry of a small surface-mounted PM synchronous machine has been chosen as reference, and the influence on the machine performance of conventional single-layer and multilayer magnets have been studied. In detail, the back-EMF, output torque, torque ripple, losses, efficiency, and the cost have been assessed.