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Abstract
In recent years the application of active magnetic bearings (AMB), as supporting element as well as vibration controller for rotors, has attracted considerable attention from researchers. In this work an attempt has been made for the complete levitation of a rotor weighing 4 kg, supported on two radial active magnetic bearings and two axial passive magnetic bearings (PMB) resulting in 5-axes levitation. The active bearings working in the mode of attraction make the system inherently unstable. Herein, a direct output feedback control scheme based on proportional and derivative of position signal has been employed to achieve stability. The active magnetic bearings consist of electromagnetic actuators, proximity probes for position measurement, feedback controller and current feedback type power amplifier. The passive bearings consisting of axially magnetized circular permanent magnets work in the mode of repulsion. The design of the electromagnetic actuator has been carried out considering load carrying capacity of the AMB, core loss and the resistive loss in the coil, so that the temperature rise in the core as well as in the coil is within allowable limit. Design of the feedback controller is based on direct output feedback control scheme, which makes the controller design easier and implementation of the controller hardware becomes simpler. The feedback controller parameters have been selected appropriately to generate required stiffness and damping in the AMBs for stable levitation of the rotor. The rotor has been driven up to a speed of 2000 rpm.
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References
- Earnshaw, S., "On the Nature of the Molecular Forces", Trans. Cambridge Phil. Soc., Vol.7,1842, p.97.
- Zlotykamien., "The Active Magnetic Bearings Enables Optimum Control of Machine Vibrations", 4th International Conference on Vibrations in Rotating Machinery, Edinburgh, Scotland, September 1988.
- Schweitzer, G., Hannes Bleuler. and Alfons Traxler., "Active Magnetic Bearings", vdf Hochschulverlag AG, ETH, Zurich, 1994.
- Larsonneur, R., Siegwart, R. and Traxler, A., "Active Magnetic Bearing Control Strategies for Solving Vibration Problems in Industrial Rotor Systems", ImechE, C432/088, 1992, pp. 26-30.
- Shiau, T. N., Sheu, G. J. and Yang, C. D., "Vibration and Control of Flexible Rotor in Magnetic Bearings using Hybrid Method and Hoo Control Theory", Transaction of ASME, Journal of Engineering for Gas Turbine and Power, Vol.119, January 1997, pp.178-185.
- Kamala, V.K., Muthu, P., Chaudhary, U.K. and Rajamani, A., "Some Experiments on Magnetically Suspended Test Rotor", Indian Journal of Tribology, Vol.1 No.1 April 2002, p. 25.
- Soumendu Jana., "Studies on the Dynamics and Control of Flexible Rotor Supported with Active Magnetic Bearings", Ph.D. Thesis, Indian Institute of Kharagpur, India, 1998.
- Meirovitch, L., "Dynamics and Control of Structures", John Wiley and Sons, 1990.
- Soumendu Jana., Arun Kumar, V., Ananda, M. and Munirathnam, V., "Demonstration of 5-axes Levitation of a Rotor towards Indigenisation of Magnetic Bearing Technology", Project Document PR 04 08, National Aerospace Laboratories, Bangalore, 2004
References
Earnshaw, S., "On the Nature of the Molecular Forces", Trans. Cambridge Phil. Soc., Vol.7,1842, p.97.
Zlotykamien., "The Active Magnetic Bearings Enables Optimum Control of Machine Vibrations", 4th International Conference on Vibrations in Rotating Machinery, Edinburgh, Scotland, September 1988.
Schweitzer, G., Hannes Bleuler. and Alfons Traxler., "Active Magnetic Bearings", vdf Hochschulverlag AG, ETH, Zurich, 1994.
Larsonneur, R., Siegwart, R. and Traxler, A., "Active Magnetic Bearing Control Strategies for Solving Vibration Problems in Industrial Rotor Systems", ImechE, C432/088, 1992, pp. 26-30.
Shiau, T. N., Sheu, G. J. and Yang, C. D., "Vibration and Control of Flexible Rotor in Magnetic Bearings using Hybrid Method and Hoo Control Theory", Transaction of ASME, Journal of Engineering for Gas Turbine and Power, Vol.119, January 1997, pp.178-185.
Kamala, V.K., Muthu, P., Chaudhary, U.K. and Rajamani, A., "Some Experiments on Magnetically Suspended Test Rotor", Indian Journal of Tribology, Vol.1 No.1 April 2002, p. 25.
Soumendu Jana., "Studies on the Dynamics and Control of Flexible Rotor Supported with Active Magnetic Bearings", Ph.D. Thesis, Indian Institute of Kharagpur, India, 1998.
Meirovitch, L., "Dynamics and Control of Structures", John Wiley and Sons, 1990.
Soumendu Jana., Arun Kumar, V., Ananda, M. and Munirathnam, V., "Demonstration of 5-axes Levitation of a Rotor towards Indigenisation of Magnetic Bearing Technology", Project Document PR 04 08, National Aerospace Laboratories, Bangalore, 2004