Title:
PERMANENT MAGNET ELECTRIC MACHINE HAVING REDUCED COGGING TORQUE
Document Type and Number:
WIPO Patent Application WO2002037643
Kind Code:
A3
Abstract:
A permanent magnet electric machine includes a stator with salient stator poles. A rotor (16) includes two or more axial rotor sections (72,74) that are rotationally offset by an offset angle equal to the cogging angle divided by the number of axial rotor sections. The axial rotor sections include rotor poles with permanent magnets (40). In one embodiment, the permanent magnet electric machine has a 12/10 slot/pole combination. The permanent magnets have a magnet dimension angle between 31 and 35 degrees. An air gap ratio of the electric machine is between 1.35 and 2.5. A slot opening ratio of the electric machine is less than or equal to one. In another embodiment, the permanent magnet electric machine has an 18/12 slot/pole combination. The permanent magnets have a magnet dimension angle that is between 25 and 28 degrees. An air gap ratio of the electric machine is between 1.35 and 2.5. A slot opening ratio of the electric machine is less than or equal to one.
Inventors:
WALLS TODD
CRAPO ALAN
CRAPO ALAN
Application Number:
PCT/US2001/047293
Publication Date:
October 10, 2002
Filing Date:
October 30, 2001
Export Citation:
Assignee:
EMERSON ELECTRIC CO (US)
International Classes:
H02K29/03; (IPC1-7): H02K29/03; H02K1/27
Foreign References:
| EP0300042A1 | 1989-01-25 | |||
| US6034460A | 2000-03-07 | |||
| EP0449538A1 | 1991-10-02 | |||
| EP0564759A1 | 1993-10-13 | |||
| US5397951A | 1995-03-14 |
Other References:
PATENT ABSTRACTS OF JAPAN vol. 011, no. 031 (E - 475) 29 January 1987 (1987-01-29)
ACKERMANN B ET AL: "New technique for reducing cogging torque in a class of brushless DC motors", IEE PROCEEDINGS B (ELECTRIC POWER APPLICATIONS), JULY 1992, UK, vol. 139, no. 4, pages 315 - 320, XP002209198, ISSN: 0143-7038
CHEN S X ET AL: "THE ROBUST DESIGN APPROACH FOR REDUCING COGGING TORQUE IN PERMANENT MAGNET MOTORS", IEEE TRANSACTIONS ON MAGNETICS, IEEE INC. NEW YORK, US, vol. 34, no. 4, PART 1, July 1998 (1998-07-01), pages 2135 - 2137, XP000833296, ISSN: 0018-9464
ACKERMANN B ET AL: "New technique for reducing cogging torque in a class of brushless DC motors", IEE PROCEEDINGS B (ELECTRIC POWER APPLICATIONS), JULY 1992, UK, vol. 139, no. 4, pages 315 - 320, XP002209198, ISSN: 0143-7038
CHEN S X ET AL: "THE ROBUST DESIGN APPROACH FOR REDUCING COGGING TORQUE IN PERMANENT MAGNET MOTORS", IEEE TRANSACTIONS ON MAGNETICS, IEEE INC. NEW YORK, US, vol. 34, no. 4, PART 1, July 1998 (1998-07-01), pages 2135 - 2137, XP000833296, ISSN: 0018-9464
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