Self-Bearing Machine Modeling Reflecting Rotor Position Induced Non-Linearity Based on 7-D Lookup Table

Ye Gu Kang, Daniel Fernandez

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


The rotor of self-bearing machines can be in an off-centered position as they lack of physical bearings. The air-gap length and effective area with respect to each phase become nonuniform, which results in inductance and back EMF non-linearities. Evaluation of self-bearing machines performance in time domain is inaccurate without a model that includes non-linear inductance and back EMF constants. To reflect non-linearities, finite element analysis (FEA) is often used. However, FEA requires large computational power to run in time-domain simulation. In this article, a 7-D lookup table (7-D LUT) model of inductance and back EMF constants, suspension forces, and torque is proposed for time-domain simulation, including non-linearity from the rotor translational and rotational displacement. Pre-evaluated FEA results are post-processed to construct the 7-D LUT model to enable fast and accurate time-domain simulation reflecting non-linearities from the input of rotary position (slotting effect), translational position in horizontal and vertical directions (unbalanced air-gap field effect), and magnetic saturation effect. A combined winding self-bearing machine is evaluated using the proposed method and verified with FEA and experimental results.

Original languageEnglish
Pages (from-to)1-10
Number of pages10
JournalIEEE Transactions on Magnetics
Issue number11
StatePublished - 1 Nov 2021


  • Eccentricity
  • finite element analysis (FEA)
  • lookup table (LUT)
  • machine model
  • self-bearing machine
  • self-bearing permanent magnet synchronous machines (BPMSMs)


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