Permanent magnet electric motor and method of making same
US6788013B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 2003 |
| Grant date | Sep 7, 2004 |
| Priority date | — |
| Expiry date | Feb 10, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02K2201/06
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A motor for reducing torque ripple includes a shaft having a shaft axis, a rotor positioned about the shaft, a first magnet ring positioned on the rotor, the first magnet ring having magnets each occupying a magnet angle &dgr; on the rotor, and a second magnet ring positioned on the rotor, the second magnet ring having magnets each occupying a magnet angle &dgr; on the rotor, wherein the second magnet ring is shifted a non-zero number of degrees relative to the first magnet ring and wherein ends of each magnet within the second magnet ring are located at different angular positions than ends of each magnet within the first magnet ring relative to the shaft axis of the shaft. The magnet angle &dgr; is preferably an optimal magnet angle for minimizing cogging torque and line to line back emf harmonics. A method of determining the optimal magnet angle includes determining a first magnet angle where cogging torque is minimized, determining a second magnet angle where harmonic content of nth harmonic is minimized, and using the first magnet angle and the second magnet angle, determining an optimal magnet angle for minimizing both cogging torque and nth harmonic.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.