US Patent 7432626 Dynamoelectric machine having reduced magnetic noise and method

An automotive alternator including a rotor having a plurality of poles; a plurality of phases in operable communication with the plurality of poles; and a stator core in operable communication with the rotor, the stator having a number of slots defined by:S=(P×PH)+((M×PH)+N)where S=number of slotsP=number of polesPH=number of phasesM=a whole integer greater than or equal to 0N=a whole integer selected from a group of integers ranging from, and including, 1 through the number of phases minus 1.A method for reducing magnetic noise in an automotive alternator includes selecting a number of poles, selecting a number of phases, selecting a number of stator core slots, the foregoing selections interacting in the automotive alternator to produce an order of frequency of a tangential force different than any multiple of the number of phases and different than an order of frequency of a radial force of the alternator.