Modeling and Simulation of a Compressor Installed with Active Magnetic Bearings Exploiting Feedforward Control

The present paper focuses on non-linear numerical modeling of active magnetic bearings (AMBs) in a compressor system. The rotor is modeled through a FEM approach and external disturbances are considered as constant and variable loads. Constant loads arise from nominal compressor operation and variable loads are shocks described by a known acceleration profile. Proportional-Integral-Derivative (PID) position controllers are coupled with feedforward (FF) control for the AMBs to mitigate variable load effects on the rotor. FF control is an adaptable static gain dependent on the versus of the imposed shock. Proportional-Integral (PI) current controllers reflect power electronics behaviour. Simulation results indicate that displacements for the most loaded radial AMB are 40% and 44% of the nominal air gap, for negative and positive shocks respectively. Displacements for the axial AMB are 30% and 54% of the nominal airgap for negative and positive shocks respectively. The implemented control scheme proves effective in mitigating the effects of known external disturbances.