Suspension force model for bearingless AC homopolar machines designed for flywheel energy storage

Eric Severson, Robert Nilssen, Tore Undeland, Ned Mohan

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Scopus citations

Abstract

Bearingless ac homopolar machines combine magnetic bearing and motor/generator functionality into a single electric machine which features variable excitation, high power density at high rotational speed, a simple and robust rotor structure, and magnet-less excitation. These features make the bearingless ac homopolar machine a promising machine for highspeed flywheel energy storage systems (FESS). The variable excitation of the bearingless ac homopolar machine has the potential to increase the FESS's efficiency by allowing for low excitation during periods of free-wheeling and high-speed operation. However, the magnetic suspension's position stiffness and current stiffness depend upon the excitation level. This dependency must be taken into account in the suspension controller or the magnetic suspension may become unstable at certain excitation levels. A technique for modeling this dependence is presented in this paper and explored through 3D finite element simulation. A prototype design is analyzed for two rotor structures: one with a square airgap length profile and one with an inverted sinusoidal airgap length profile.

Original languageEnglish (US)
Title of host publication2013 7th IEEE GCC Conference and Exhibition, GCC 2013
Pages274-279
Number of pages6
DOIs
StatePublished - 2013
Event2013 7th IEEE GCC Conference and Exhibition, GCC 2013 - Doha, Qatar
Duration: Nov 17 2013Nov 20 2013

Publication series

Name2013 7th IEEE GCC Conference and Exhibition, GCC 2013

Other

Other2013 7th IEEE GCC Conference and Exhibition, GCC 2013
CountryQatar
CityDoha
Period11/17/1311/20/13

Keywords

  • ac homopolar machine
  • active magnetic bearing
  • flywheel energy storage

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    Severson, E., Nilssen, R., Undeland, T., & Mohan, N. (2013). Suspension force model for bearingless AC homopolar machines designed for flywheel energy storage. In 2013 7th IEEE GCC Conference and Exhibition, GCC 2013 (pp. 274-279). [6705789] (2013 7th IEEE GCC Conference and Exhibition, GCC 2013). https://doi.org/10.1109/IEEEGCC.2013.6705789