A ROTOR LAMINATION DESIGN FOR SURFACE PERMANENT-MAGNET RETENTION AT HIGH SPEEDS

A major problem in the design and manufacturing of surface mounted per manent magnet machines is reliably holding the permanent magnets in pl ace at high speeds. This paper evaluates a unique rotor lamination des ign for a high pole number, permanent magnet alternator. This buried m agnet design, which is capable of reliably holding the permanent magne ts in place at high speeds, offers both easier and cheaper assembly wh en compared with the methods currently used in surface mounted permane nt magnet machines, Finite element analysis is used to compare the bur ied magnet design with equivalent surface mounted designs and shows th at the performance of the alternator is not significantly affected by the iron over the magnets. Experimental results from a prototype alter nator further corroborate the FEA acid show that the design is capable of operating at high speeds with no other means of magnet retention. In addition, an improvement in the buried magnet design which can redu ce the lamination complexity is suggested and examined.