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Chen, Ouyang

University of British Columbia

Bearingless motors, whose rotors are magnetically suspended without physical contact, show advantages in applications that require high speed and clean working environment. However, due to the natural instability of radial displacements, radial suspension control is essential for rotor operation. In this thesis, we improve the suspension control performance for our dipole interior permanent magnet bearingless slice motor by developing a new current-to-force model and re-designing suspension controller for eliminating self-excitation behaviour. The proposed suspension force model, derived using magnetic co-energy method and verified by finite element analysis, aims to reduce the radial displacements and increase stability of suspension comparing to the conventional model. Radial displacement measurements show that our proposed model significantly reduces radial displacements at high speed and increases the maximum speed of the rotor. We also investigate the undesired self-excitation behaviour that the rotor speed is maintained even if the torque command is zero. Stress tensor method and finite element analysis indicate that additional torque is generated due to rotor eccentricity. The self-excitation behaviour is eliminated by suppressing the peak of the suspension loop sensitivity function, so as to reduce the maximum rotor eccentricity during the rotation.

Text

2023-08-31

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85732

Mechanical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/