Methods and apparatus for an electric machine with a cast rotor
View Patent ↗A squirrel cage rotor structure used in connection with an electrical machine is formed from a high-strength, high-conductivity, and heat-treatable aluminum alloy, e.g., a T61 tempered aluminum alloy, such as A6101-T61. The resulting structure has improved strength compared to conventional pure aluminum structures, while at the same time limiting the reduction in electrical conductivity.
1. An electrical machine comprising:
a stator; and
a rotor configured to rotate coaxially with respect to the stator and magnetically interact therewith, the rotor including a plurality of substantially parallel metallic laminations;
wherein the rotor includes a squirrel-cage structure comprising a heat-treatable wrought aluminum alloy including Si and Mg and die cast around the substantially parallel metallic laminations.
2. The electrical machine of claim 1 , wherein the aluminum alloy has an electrical conductivity above 49% IACS.
3. The electrical machine of claim 2 , wherein the aluminum alloy has a yield strength of greater than about 85 MPa.
4. The electrical machine of claim 1 , wherein the aluminum alloy has a temper selected from the group consisting of T1, T5, T6, T61, T62, T63, T64, T65, T81, and T83.
5. The electrical machine of claim 4 , wherein the aluminum alloy is an A6101 aluminum.
6. The electrical machine of claim 1 , wherein the squirrel cage structure is a wrought aluminum alloy structure.
7. The electrical machine of claim 1 , wherein the squirrel cage structure is selected from the group consisting of a die-cast aluminum alloy structure, a sand-cast structure, and a squeeze cast structure.
8. The electrical machine of claim 1 , wherein the squirrel cage structure includes two end rings having a plurality of parallel-oriented conductor bars extending therebetween.
9. A method of manufacturing a rotor for an electrical machine, comprising:
providing a plurality of metallic laminations;
assembling the plurality of laminations substantially parallel to each other, thereby forming a rotor stack;
forming a die cast aluminum alloy squirrel-cage structure such that it substantially encompasses the rotor stack, wherein the aluminum alloy comprises Si and Mg; and
heat treating the die cast wrought aluminum alloy squirrel-cage structure.
10. The method of claim 9 , wherein the aluminum alloy has an electrical conductivity above 49% IACS.
11. The method of claim 10 , wherein the aluminum alloy has a yield strength of greater than 85 MPa.
12. The method of claim 9 , wherein the aluminum alloy is an A6101 alloy with a temper selected from the group consisting of T1, T5, T6, T61, T62, T63, T64, T65, T81, and T83.
13. A rotor for an electrical machine, comprising:
a rotor stack comprising a plurality of substantially parallel metallic laminations; and
a die cast aluminum alloy squirrel-cage structure at least partially encompassing the rotor stack;
wherein the aluminum alloy comprises Si and Mg, is heat treatable, has an electrical conductivity above 49% IACS, and has a yield strength of greater than 85 MPa.