Methods and apparatus for a permanent magnet machine with asymmetrical rotor magnets
In general, the various embodiments are directed to a permanent magnet machine (“PM machine”), and more specifically an internal permanent magnet machine (“IPM machine”) that includes rotor magnets configured asymmetrically with respect to the rotor periphery, thereby producing an averaging effect similar to that achieved through traditional skewing of the rotor magnets. In alternate embodiments, the span, placement and/or shape of the magnets may vary from one pole to the next.
1. An interior permanent magnet machine comprising:
a stator;
a rotor configured to magnetically interact with the stator, the rotor having an outer surface and a plurality of poles defined by respective pole axes;
a plurality of rotor barriers provided within the rotor; and
a plurality of permanent magnets disposed within the rotor such that the magnets are configured asymmetrically with respect to the pole axes;
wherein the plurality of poles comprises a first pole and a second pole, and wherein the magnets within the first pole do not have the same asymmetrical configuration as the magnets within the second pole, and wherein the plurality of magnets are configured in pairs defining a concave angle toward the outer surface of the rotor.
2. The interior permanent magnet machine of claim 1 , wherein the magnets within each pole are substantially the same size and shape, but are asymmetrically spaced with respect to the pole axes.
3. The interior permanent magnet machine of claim 1 , wherein the magnets within each pole have different sizes.
4. The interior permanent magnet machine of claim 1 , wherein the magnets within each pole have different shapes.
5. The interior permanent magnet machine of claim 1 , wherein the plurality of magnets are ferrite magnets.
6. A method of making an interior permanent magnet machine, comprising:
providing a stator;
providing a rotor configured to magnetically interact with the stator, the rotor having an outer surface and a plurality of poles;
forming a plurality of rotor barriers within the rotor;
placing a plurality of permanent magnets within the rotor such that the rotor barriers are asymmetrical with respect to their respective pole axes, the plurality of poles comprises a first pole and a second pole, the magnets within the first pole do not have the same asymmetrical configuration as the magnets within the second pole, and the plurality of magnets are configured in pairs defining a concave angle toward the outer surface of the rotor.
7. The method of claim 6 , wherein the magnets within each pole are substantially the same size and shape, but are asymmetrically spaced with respect to the pole axes.
8. The method of claim 6 , wherein the magnets within each pole have different sizes.
9. The method of claim 6 , wherein the magnets within each pole have different shapes.
10. The method of claim 6 , wherein the plurality of magnets are ferrite magnets.
11. A traction motor of the type used in connection with a hybrid electric vehicle, the traction motor comprising:
a stator;
a rotor configured to magnetically interact with the stator, the rotor having an outer surface and a plurality of poles defined by respective pole axes;
a plurality of rotor barriers provided within the rotor; and
a plurality of permanent magnets disposed within the rotor such that the magnets are configured to produce rotor barrier asymmetry;
wherein the plurality of poles comprises a first pole and a second pole, and wherein the magnets within the first pole do not have the same asymmetrical configuration as the magnets within the second pole, and wherein the plurality of magnets are configured in pairs defining a concave angle toward the outer surface of the rotor.
12. The traction motor of claim 11 , wherein the magnets within each pole are substantially the same size and shape, but are asymmetrically spaced with respect to the pole axes.
13. The traction motor of claim 11 , wherein the magnets within each pole have different sizes.
14. The traction motor of claim 11 , wherein the magnets within each pole have different shapes.