Patent · US Expired

Permanent magnet excited electric motor with improved torque ripple

US5331245A · kind A · utility

63Cited by

10References

16Claims

0Family size

Assignee

Papst Licensing GmbH · DE

Inventors

Martin Burgbacher · St. Georgen, DE
Michael Hermann · Tacherting, DE

Key dates

Filing date	Jul 23, 1991
Grant date	Jul 19, 1994
Priority date	—
Expiry date	Jul 23, 2011

Classification

Technology area (CPC H)Electricity
CPC primaryH02K21/22
WIPO fieldElectrical machinery, apparatus, energy
WIPO sectorElectrical engineering

Abstract

A brushless direct current motor has a substantially cylindrical, external permanent magnet rotor having a plurality of north poles and south poles. The rotor surrounds a substantially cylindrical stator provided with a plurality of main poles between which auxiliary poles are interspersed. An annular gap is defined between the rotor and the stator. To reduce magnetic or reluctance caused fluctuation of the motor torque, each main pole of the stator has an angular extent which substantially corresponds to that of a rotor pole. Furthermore, the stator periphery is provided with protuberances arranged such that permanently magnetically caused components of torque ripple are reduced.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.