Cogging Torque Definitions for Magnetic Gears and Magnetically Geared Electrical Machines

Although cogging torque in magnetic gears (MGs) has been studied, the additional degree of freedom inherent to MGs makes it unclear exactly what is defined as the cogging torque of a MG. Although MGs generally have relatively smooth torque transfer characteristics, this paper reveals that when the g...

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Bibliographic Details
Published in:IEEE transactions on magnetics 2018-04, Vol.54 (4), p.1-9
Main Authors: Gerber, Stiaan, Wang, Rong-Jie
Format: Article
Language:English
Subjects:
Cogging
Cogging torque
dynamic modeling
Electric machines
Gears
Magnetic gears
magnetic gears (MGs)
Magnetism
Mathematical analysis
Torque
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Summary:Although cogging torque in magnetic gears (MGs) has been studied, the additional degree of freedom inherent to MGs makes it unclear exactly what is defined as the cogging torque of a MG. Although MGs generally have relatively smooth torque transfer characteristics, this paper reveals that when the gear is used in an up-speed configuration, cogging effects may be amplified under startup conditions. This paper distinguishes between two kinds of cogging torque in MGs, termed the synchronous cogging torque and the true cogging torque. Calculation of the true cogging torque is more difficult than the synchronous cogging torque, but an approximation to the true cogging torque can be obtained using the synchronous cogging torque. The theory is verified experimentally and supported further by results from dynamic simulations. The impact on magnetically geared machines is also considered.
ISSN:0018-9464
1941-0069
DOI:10.1109/TMAG.2017.2784823