Vibration Control in a Co-rotating Twin-Spool Rotor System Under Base Excitation and Mass Unbalance Using Active Magnetic Bearings

PurposeActive magnetic bearing (AMB) is designed and optimized for contactless support and active vibration control in a flexible twin-spool rotor system subjected to mass unbalance and harmonic base excitation. A multiobjective genetic algorithm is utilized to optimize the AMBs supporting the inner rotor. The primary aim of this analysis is to control the vibration amplitude within a tolerable range at those positions along the rotor where AMBs and disks are located. Besides, a comparative study is also performed to investigate the effect of increasing the mass unbalance on AMB design parameters.MethodsThe system response is evaluated through a finite element method (FEM) based vibration analysis, for which the mathematical model is developed using the Lagrangian approach with due consideration to the rotary inertia and shear effects. For rotordynamic analysis and implementation of multiobjective genetic algorithm, MATLAB codes have been developed.Results and ConclusionWith optimized design parameters, a maximum reduction of 73.66% in the amplitude peak is obtained at the AMBs locations. Besides, it has been found that forward and backward whirling modes get excited due to mass unbalance and base excitation. Also, it is found that on increasing the mass unbalance, the optimum number of turns, pole width and length are found to increase by 32.87%, 23.16% and 15.42%, respectively.