Patent ID: 7714473

Claim:
An electrical machine including a first body having a plurality of circumferentially spaced winding slots formed at its radially inner surface, and a second body located within the first body and having a plurality of circumferentially spaced magnet poles formed at its radially outer surface, one of the first and the second bodies being a rotatably mounted rotor, and the other of the first and the second bodies being a fixedly mounted stator, the winding slots having a reference angular pitch that is equal to 360° divided by a number of the winding slots in the electrical machine; the magnet poles comprising at least a first group including at least four circumferentially adjacent magnet poles, and a second group including at least four circumferentially adjacent magnet poles, the first group and the second group including a same number of magnet poles and having a same displacement pattern; each magnet pole having a reference position, the reference positions being equally spaced around a circumference of the second body; the displacement pattern of the magnet poles in the first and second groups being determined according to a formula: D = 2 ⁢ ( p - 1 ) N where: D=an angular displacement in winding slot pitches of magnet pole p from its reference position, p=a magnet pole number within the first or second group, and counted from the closest adjacent magnet pole group, and N=the number of magnet poles in the first or second group; at least one magnet pole in each of the first and second groups being a circumferentially outermost magnet pole and being located in its reference position as a result of said formula; and at least one magnet pole in each of the first and second groups being a displaced magnet pole and being located in a position that is displaced from its reference position as a result of said formula by an amount that is not equal to an integral multiple of the reference angular pitch of the winding slots.