PERMANENT MAGNET MOTORS WITH FLUX FOUNTAIN OUTRUNNER
A rotor for an electric machine includes a housing, a plurality of arc-shaped magnets disposed in the housing, and a plurality of separators interposed between the magnets. The magnets have a coercivity (Hci) of 2000 Oe (oersted) to 4000 Oe, and a magnetization direction of the magnets is in a circumferential orientation with respect to the housing.
1 . A rotor comprising:
a housing;
a plurality of arc-shaped magnets disposed in the housing, wherein:
the magnets have a coercivity (Hci) of 2000 Oe (oersted) to 4000 Oe; and
a magnetization direction of the magnets is in a circumferential orientation with respect to the housing; and
a plurality of separators interposed between the magnets.
2 . The rotor of claim 1 , wherein the housing is formed of a nonferrous material, and a length of each of the magnets as measured in the magnetization direction is at least 10 times a thickness of the housing.
3 . The rotor of claim 2 , wherein the nonferrous material includes one or more of: aluminum, stainless steel, plastic, titanium, titanium alloy, magnesium, or magnesium alloy.
4 . The rotor of claim 1 , wherein the separators are formed of a ferrous alloy.
5 . The rotor of claim 1 , wherein the magnets maintain a magnetic flux density of at least 0.5 T (tesla) during operation.
6 . The rotor of claim 1 , wherein the magnets include iron nitride (FeN) magnets.
7 . The rotor of claim 1 , wherein the separators are arc-shaped.
8 . The rotor of claim 7 , wherein a total sum of arc angles of the separators and of the magnets equals 360 degrees.
9 . The rotor of claim 7 , wherein a number of the magnets equals a number of the separators.
10 . The rotor of claim 9 , wherein the magnets have an arc angle (θ m ), and the separators have an arc angle (θ s ) such that (θ m +θ s )*n=360, in degrees, where n is the number of the magnets in the rotor.
11 . The rotor of claim 9 , wherein the number of the magnets is eight (8).
12 . The rotor of claim 1 , wherein the separators are in direct contact with the magnets.
13 . The rotor of claim 1 , wherein magnetization directions of two neighboring magnets of the arc-shaped magnets are in opposite directions with respect to each other to facilitate alternating polarities.
14 . The rotor of claim 1 , wherein the magnets are formed using only non-strategic-mineral materials.
15 . The rotor of claim 1 , wherein the magnets are formed using only non-rare-earth-metal materials.
16 . The rotor of claim 1 , wherein the separators include steel poles.
17 . The rotor of claim 1 , wherein the magnetization direction of the magnets is in a transverse orientation with respect to a magnetic airgap of the rotor.
18 . An electric machine comprising:
the rotor of claim 17 ; and
a stator disposed in the rotor, wherein the magnetic airgap is located between the rotor and the stator.
19 . A rotor comprising:
a nonferrous housing;
a plurality of arc-shaped iron nitride (FeN) magnets disposed in the housing, wherein a magnetization direction of the FeN magnets is in a circumferential orientation with respect to the housing; and
a plurality of ferrous separators interposed between the FeN magnets.