Abstract of Thesis presented at COPPE/UFRJ as a partial fulfillment of the requirements for the degree of Doctor of Science (D.Sc.)

Performance Assessment Criteria for Controllers Applied to Magnetic Bearings

José Dalvio Ghirello Garcia

July/2014

Advisors:

Richard Magdalena Stephan Afonso Celso Del Nero Gomes

Department:

Eletrical Engineering

      Active Magnetic Bearings have being used, nowadays more frequently, in industrial applications. The fact that they are based on magnetic fields results in their inherently instability, requiring the use of controllers to attain stability. Different control structures have been proposed and tested, as literature presents papers by many authors addressing this subject. The question that arises from this diversity is which control algorithm is the best.
      This thesis analyzes controllers’ performance, applying two different evaluation criteria, namely the minimum variance criteria and the minimum displacement criteria with sensitivity analysis, proposed by ISO14839 norm. Experimental data for LQR and PID controllers used to stabilize the existing bearingless motor, at UFRJ Applied Superconductor Laboratory, is employed to evaluate their performance. Conclusion is reached that, for this specific application, LQR controller displays the best performance.