Adaptive nonlinear controller of rotor position in active hybrid bearings

The process of improving the rotating machinery is tightly connected with reduction of vibrations level. It can be implemented by using active bearings. The present paper considers the control system of the active hybrid fluid-film bearing. The closed-loop system allows controlling the rotor position. In general, conventional controllers based on a PID law cope with such problems rather well. However, in many cases the more advanced controllers can show better results. Therefore, a nonlinear controller with adaptive gain coefficient has been developed during the research. The control law considers the features of operation of a hybrid fluid-film bearing. The resulting system allows effective holding the rotor position within the preset limits under variable load. The controller also allows avoiding the excessive vibrations reduction since it is not necessary in most cases. The considered active hybrid bearings can be used in rotating machinery exposed to excessive vibrations and complex loads. In particular, they can be successfully used in rotating machines equipped with automatic balancing systems where the complex loads are caused by operation of the auto-balancing device itself.