Robust Performance Analysis of Magnetic Bearings

Toru Namerikawa, Masayuki Fujita

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


This paper deals with uncertain model structures, model validation and robust performance analysis of active magnetic bearings. The dynamics of active magnetic bearing systems are characterized by their instability and complex dynamics of rotor and electromagnets. The feedback control is indispensable to stabilize the system, further the closed-loop systems of magnetic bearings should have robustness for stability and performance against model uncertainties. First we derive a nominal mathematical model of AMBs as a linear state-space model under some assumption and idealization, then we consider the disconlineancy between the real physical systems and the obtained nominal design model. This disconlineancy can be expressed as the structured uncertainties by Linear Fractional Transformation. These uncertainties include linearization error, parametric uncertainties, unmodeled dynamics, and gyroscopic effect. Then we set the interconnection structure which contains the above structurally onlineresented uncertainties. Next we design a robust controller which achieves robust performance condition. Finally, we validate the interconnection structure with the nominal model and uncertainties, and analyze the robustness of stability and performance of the closed-loop system via the mixed structured singular value.

Original languageEnglish
Pages (from-to)1061-1067
Number of pages7
Journalieej transactions on industry applications
Issue number10
Publication statusPublished - 2001 Sept 1
Externally publishedYes


  • Linear Fractional Transformation
  • Magnetic Bearings
  • Robust Control
  • Uncertain Model
  • μ-Analysis and Synthesis

ASJC Scopus subject areas

  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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