Nonlinear instabilities induced by the F coil power amplifier at FTU: Modeling and control

L. Zaccarian, L. Boncagni, D. Cascone, C. Centioli, S. Cerino, F. Gravanti, F. Iannone, F. Mecocci, L. Pangione, S. Podda, V. Vitale, R. Vitelli

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8 Citations (Scopus)


In this paper we focus on the instabilities caused by the nonlinear behavior of the F coil current amplifier at FTU. This behavior induces closed-loop instability of the horizontal position stabilizing loop whenever the requested current is below the circulating current level. In the paper we first illustrate a modeling phase where nonlinear dynamics are derived and identified to reproduce the open-loop responses measured by the F coil current amplifier. The derived model is shown to successfully reproduce the experimental behavior by direct comparison with experimental data. Based on this dynamic model, we then reproduce the closed-loop scenario of the experiment and show that the proposed nonlinear model successfully reproduces the nonlinear instabilities experienced in the experimental sessions. Given the simulation setup, we next propose a nonlinear control solution to this instability problem. The proposed solution is shown to recover stability in closed-loop simulations. Experimental tests are scheduled for the next experimental campaign after the FTU restart. © 2008 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)2015 - 2019
Number of pages5
JournalFusion Engineering and Design
Issue number7-11
Publication statusPublished - Jun 2009


All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Nuclear Energy and Engineering
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Zaccarian, L., Boncagni, L., Cascone, D., Centioli, C., Cerino, S., Gravanti, F., ... Vitelli, R. (2009). Nonlinear instabilities induced by the F coil power amplifier at FTU: Modeling and control. Fusion Engineering and Design, 84(7-11), 2015 - 2019.