Abstract Magnetic bearings are capable of supporting rotors in the absence of mechanical contact. A magnetic bearing is an oil-free bearing system that uses electromagnetic forces to maintain the relative position of a rotating assembly (rotor) relative to a fixed component (stator). In the past decades, there has been a growing interest in passive magnetic bearings capable of generating positive stiffness using eddy current forces. Systems that implement this concept for rotor floating are commonly known as electrodynamic bearings. This research deals with the dynamic behavior of a rotor with an active magnetic bearing with a state feedback controller. Rotor vibrations have been modeled using second-order nonlinear differential equations with quadratic an‎d cubic nonlinear factors, an‎d assuming weak nonlinear factors an‎d soft excitation, multiple scales method has been used to solve differential equations an‎d frequency diagrams have been obtained. The results show that with the increase of the derivative coefficient of the controller, the behavior of the system becomes closer to the behavior of the linear system, an‎d with the increase of the adjustment frequency, the behavior of the system is out of the linear state an‎d jump phenomena are observed. The obtained results indicate that the response range of the system is fluctuating an‎d stable, an‎d the phase diagrams tend towards a limit cycle. Due to the fact that the excitation is weak, the fuzzy diagrams in both horizontal an‎d vertical directions have obtained almost small displacement an‎d velocity values, an‎d the unbalanced excitation force an‎d the excitation force caused by nonlinear terms have almost the same contribution to the systemʹs phase form.

مصطفي نصيري

ابوالحسن عسگر شمسي , مصطفي منيري