Homopolar Bearingless Slice Motor With Flux-Biasing Halbach Arrays

In this article, we present a new configuration of bearingless slice motor that levitates and rotates a ring-shaped solid steel reluctance rotor. The rotor is 50 mm in diameter and has salient features on the outer surface. Symmetric sets of Halbach magnet arrays, mounted on the tips of stator teeth...

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Bibliographic Details
Published in:IEEE transactions on industrial electronics (1982) 2020-09, Vol.67 (9), p.7757-7766
Main Authors: Noh, Minkyun, Trumper, David L.
Format: Article
Language:English
Subjects:
Air gaps
Arrays
Bearingless motors
Bias
Feedback control
Flux
flux biasing
homopolar machines
Magnetic flux
Magnetic levitation
Permanent magnets
Prototypes
Reluctance motors
Rotors
slice motors
Stator windings
Synchronous machines
Torque
Translations
Windings
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Summary:In this article, we present a new configuration of bearingless slice motor that levitates and rotates a ring-shaped solid steel reluctance rotor. The rotor is 50 mm in diameter and has salient features on the outer surface. Symmetric sets of Halbach magnet arrays, mounted on the tips of stator teeth, establish a homopolar bias flux around the rotor. The bias flux passively stabilizes the rotor in the out-of-plane tilts and axial translation, whereas the rotor's radial translations are actively stabilized by feedback control. The rotor saliencies spatially modulate the air-gap bias flux such that the resulting torque-current relationship is similar to that of permanent-magnet synchronous machines. We have designed, built, and tested a prototype bearingless motor and control system. The prototype system achieves a torque constant of 14.9 mNm/A, maximum speed of 5500 r/min, and suspension bandwidth of 84 Hz with a phase margin of 11.3°. The rated torque and speed are 26.8 mNm and 3486 r/min, respectively, and the axial and tilting passive stiffnesses are 15.3 N/mm and 34.4 mNm/°, respectively.
ISSN:0278-0046
1557-9948
DOI:10.1109/TIE.2019.2942512