Patent attributes
An interior permanent magnet machine including a rotor stack defining at least two adjacent magnet retention slots and a plurality of permanent magnets positioned within the interior of the rotor, wherein the radial thickness of the rotor that is above a given magnet retention slot transitions from a first radial thickness to a bridge region having a second radial thickness that is less than the first radial thickness. The bridge region is positioned between the two magnet retention slots and the transition to the bridge region occurs within an area falling within a defined angular expanse. Areas of low permeability are positioned below the bridge region between the ends of the adjacent permanent magnets such that (i) there are no direct linear paths between the end edges of the two adjacent magnets that do not pass through an area of low permeability, and (ii) that there are no direct linear paths that extend radially from the outer portion of the rotor to the interior of the rotor, between the permanent magnets, that do not also pass through an area of low permeability.
