NONLINEAR CONTROL OF A MAGNETIC-LEVITATION SYSTEM WITHOUT PREMAGNETIZATION

A nonlinear model of an inertial wheel supported by active magnetic be arings is presented, A nonlinear controller based on input-output line arization is then derived to stabilize this model, This is contrasted to the typical practice of obtaining a linear model via premagnetizati on of the bearings through a bias current, Experimental results demons trate that the rotor vibration and energy consumption of the bearings are lower when the nonlinear control method Is used, A sliding mode co ntrol method is also proposed so that control is achieved with only tw o values of voltage input, in much the same manner as pulse width modu lation, Simulations are also presented to test the robustness of the s liding mode control.