Fuzzy logic control of three-pole active magnetic bearing system

Author： Agarwal Praveen Kumar Chand Satish

ISSN： 1746-6172

Source： International Journal of Modelling, Identification and Control, Vol.12, Iss.4, 2011-05, pp. : 395-411

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Abstract

Active magnetic bearings have many advantages over conventional bearings due to non-contact operation and adjustable force dynamics. The major disadvantage of magnetic bearings is its cost. In the present work, a three-pole magnetic bearing has been considered which helps in reducing the cost by having the minimum number of poles. The power loss is minimised by determining the optimum bias currents for different pole orientations. However, the strongly non-linear nature of three-pole magnetic bearing due to flux coupling necessitates the application of non-linear control techniques for its controller design. A fuzzy logic controller has been designed for the stable operation of magnetic bearing. The present design of fuzzy logic controller is done by reducing the number of rules of its rule-base. The provision for mass unbalance compensation has also been provided by combining the fuzzy logic approach with iterative learning control (ILC) approach. Simulations have been carried out to test the performance of the controller for different initial conditions. The designed controller is able to stabilise the rotor even for large deviations from the origin. The controller is found to be robust as it provides satisfactory operation in the presence of uncertainties in the magnetic bearing system.