Toroidally-Wound Self-Bearing BLDC Motor With Lorentz Force

• Published in: IEEE transactions on magnetics Vol. 46; no. 6; pp. 2148 - 2151
• Main Authors: Lee, Hak-In, Yoo, Seong-yeol, Noh, Myounggyu D.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.06.2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithm design and analysis; Algorithms; Brushless DC motors; Brushless motors; Cross-disciplinary physics: materials science; rheology; DC machines; DC motors; Exact sciences and technology; Finite element methods; Levitation; Lorentz covariance; Magnetic levitation; Magnetism; Materials science; Mathematical analysis; Mathematical models; Motors; Other topics in materials science; permanent magnet machines; Phase selection; Physics; Rotational; self-bearing motors (SBMs); Singularities; Toroidal magnetic fields; Torque; Permanent magnets; permanent magnet machines; self-bearing motors (SBMs); Machine; Magnetic properties; Magnetic levitation
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2010.2043065

Self-bearing motors (SBM) use a single magnetic structure for rotational motoring as well as for noncontact levitation. They are sometimes referred to as bearingless motors or combined motor-bearings. In this paper, we propose a new type of self-bearing motors based on toroidally-wound brushless DC machines. This type of SBM can be made to be passively stable in the axial direction and for out-of-plane rotations. To achieve self-bearing operation, we derive a force-current model and show that the levitation force is decoupled from the rotational torque. To overcome the singularity problem in the force-current model, we propose a phase selection algorithm in which the phase that may cause singularity is counted out when inverting the force-current model. Through finite element analyses and experiments, we validate the force-current model and the phase selection algorithm.