Study of active magnetic bearings (AMB) on non–synchronous rotors

A rotor is never free from vibration owing to constant centrifugal force acting on it while rotating. A practical rotor has inherent mass unevenness flaw, or bearing misalignment flaw, or self-weight bow flaw, or presence of discontinuity or cracks flaw. If the vibrations are not controlled within limits, the rotor’s purpose of existence is lost. These vibrations can be synchronous if the frequency of vibration is equal to, or multiple of, the speed of rotation of the rotor. Or may be non-synchronous if the frequency of vibration of the rotor is not a multiple of its rotational frequency. Active magnetic bearings (AMBs) have been in use for vibration control, vibration suppression, rotor stability and condition monitoring of rotordynamic systems, since many years. A lot of authors have performed various numerical and experimental works in an AMB–rotor configuration and reported their findings. The goal of this paper is to report and present the effect of AMB solely on non–synchronous rotors for the benefit of the scientific community. Firstly, this paper briefly introduces the constructional features on AMB–rotor system. Then, the gist of every paper is written, as well as specification of the work provided in tabular form. Finally, some comments on limitations and future applications are made. The paper is separately sectioned into numerical investigations, and experimental investigations.