Showing 4 results for Magnetic Bearing
Yusef. Hojjat, Mohammad. Morad. Sheikhi, Hosein . Mosavi. Hondori, Ramin. Alimohamadi,
Volume 9, Issue 1 (12-2009)
Abstract
Abstract
In recent years many researches have been focused on active magnetic bearing (AMB) systems. AMB offers advantages such as, contact less and friction free operation, excellent performance over a wide range of temperature, no need for lubricant and longer life. Technology of magnetic bearings can be considered as a new field of research in Iran. This paper presents design, manufacturing and control of a magnetically levitation system with successful operation. This research concluded with documentation of the AMB technology which is prerequisite for earning the technology of active magnetic systems (AMS) and paves the way to develop it.
Y. Hojjat, M. Mohamadi Moghadam, M. M. Sheikhi, Hosain . M. Mousavi Hondori,
Volume 10, Issue 1 (5-2010)
Abstract
An Active Magnetic Bearing (AMB) system is designed and manufactured, in which a controlled current is applied to the electromagnets of the stator by a PID controller and the generated attraction forces control the gap between rotor and stator. Effect of parameters, such as sampling frequency, excitation pattern, and the gap between rotor and stator on stability of AMB is statistically analyzed, using the experimental results. Furthermore, dynamic behavior of the system, effect of magnetic field and the resultant force, are numerically analyzed. As the system is nonlinear, experimental results are used to study the effects of nonlinearity and to control the system. In numerical analysis, the distribution and flux density of the magnetic field and the applied force on Iron shaft are calculated by Virtual Work and Maxwell Methods. In statistical analysis, the effect of frequency and gap between rotor and stator are used to determine the stable working point of the system.
Saeed Qaedi, Mostafa Ghayour, Reza Tikani,
Volume 16, Issue 1 (3-2016)
Abstract
The chaotic behavior of a flexible rotor supported by active magnetic bearings is numerically investigated in this work. A statically unbalanced disk is mounted on the the shaft. The rotor is modeled by three lumped mass and 8 D.O.F. The rotor-AMB systems include many non-linear factors, such as nonlinear function of the coil current and the air gap between the rotor and the stator, nonlinearity due to geometric coupling of magnetic actuator, eddy current effect and hysteresis losses of the magnetic core material. In this work, the influence of weight parameter on nonlinear response of the system is investigated. Numerical results showed considering of weight parameter have important effect on the response of the rotor and exhibit a rich variety of nonlinear dynamical behavior including synchronous, sub-synchronous, quasi-periodic and chaotic vibrations. Bifurcation diagrams, phase planes, power spectra ,Poincar’e map and maximum lyapanov exponents are used to analyze the response of the system under different operational conditions. Chaotic vibrations should be avoided as they induce fluctuating stresses that may lead to premature failure of the machinery’s main component. It will be beneficial to the design of AMB system.
S.h. Hosseini, M. Mahboubkhah, M. Farhid,
Volume 20, Issue 8 (8-2020)
Abstract
One of the important challenges of the aerospace industry is the use of magnetic bearings and generating the electromagnetic flux in motor to increase its speed of rotation and angular momentum. In this paper, the passive magnetic bearing for the reaction wheel actuator which is used to modify the status of space satellite is designed and analyzed using the COMSOL software. The performance of constructed reaction wheel in various modes is evaluated. In the passive magnetic bearing system, when the rotor exits the center position of the rotational axis, the return force that results from repulsion between the poles of the same permanent magnet directs the rotor to the center axis position. In the paper, the axial passive magnetic bearing is designed, and the distribution of magnetic flux density and static force of the bearing is estimated using simulation in the software and the stiffness coefficient is obtained from the static properties. To reduce the power consumption of the reaction wheel, various layouts were investigated. Then, based on design and analysis results, the appropriate bearing to achieve the maximum rotational speed and the minimum power consumption is introduced. The results of the FEM analysis clarified the effects of the magnetic stacking structure on the force and magnetic stiffness of the bearing and finally, the experiments proved that the rotational speed and momentum of the reaction wheel are increased in the combined use of the mechanical and passive magnetic bearings.
