The high magnetic energy stored in rare earthcobalt magnets a 11 ows the design of 1 i ght~tei ght motors and magnetic bearings for high speed rotors. Not subject to wear and 11i th the abi 1 i ty to operate under high vacuum conditions, magnetic bearings appear ideal for applications requiring high rotational speeds such as 100,000 rpm. Important applications are for turbomolecular pumps, lase...

Active magnetic bearings can be implemented with frequency band-reject filtering that decreases the bearing stiffness and damping at a small bandwidth around a chosen frequency. The control scheme has been used for reducing a rotor dynamic force, such as an imbalance force, transmitted to the bearing stator. This study reveals that the scheme creates additional system vibration modes at the sam...

We are developing a 50 kWh-class flywheel energy storage system as a national project, using a new axial superconducting magnetic bearing (Ax_SMB) technology. The project has started in FY2005 and will continue to FY2007. The Ax_SMB is composed of Fe core and superconducting coil, which are simply torus-shape. It generates strong restoring force in axial direction. It can realize non-contact le...

Active magnetic bearings, which are open-loop and unstable, require a feedback control system to ensure stable operation of the rotating machines that they support. Proportional-integral-derivative (PID) controllers widely used in field applications these bearings for this purpose. PID designed work effectively within linear region machines. Due inherent nonlinearity active large unbalance forc...

The contactless nature of active magnetic bearings brings about many advantages over the conventional bearing while industrial real-time applications are often limited by the significant complexity of control algorithms. This paper presents the application of an LQ controller to an active magnetic bearing system (AMB). Two control strategies are presented and compared: local and global. In the ...

Zero-bias or low-bias control of AMB's is essential for the design of magnetic bearings with low power losses. This paper investigates the use of control Lyapunov functions (clf's) to solve the problem of global asymptotic stabilization for a zero-bias Active Magnetic Bearing (AMB). We use the cascade structure of the system to derive a clf for the AMB model which is then used to derive a stabi...

The proposed work focuses on improving the performance of traditional nonlinear saturation controller (NSC) algorithm. In this work, a tuning mechanism can be implemented by providing NSC control unit with measured speed $\Omega $ rotor from shaft encoder device in order to introduce tuned (TNSC). other words, we are going tune NSC’s natural frequency ${\omega _{c}}$ at one half such that =2{\o...

Crack fault of rotor is one of the most prominent problems faced by magnetic bearing rotor system. In order to improve the safety performance of this kind of machinery, it is necessary to research the vibration characteristics of magnetic bearing cracked rotor system. In this paper, the stiffness model of the crack shaft element was established by the strain energy release rate (SERR) theory. T...

Compared to mechanical bearings, active magnetic bearings eliminate friction, resulting in lower energy losses. However, due the magnetization characteristics and high-frequency working of core material bearing, there will be high wind friction loss, eddy current hysteresis loss copper bearing. These losses generate heat increase internal temperature which not only affect control accuracy beari...