On the dynamics of rotating machinery supported by AMB during base motion

This study is devoted to rotor supported by Active Magnetic Bearings (AMBs) and subject to base motion. The machine casing is considered rigid and able to move along the 3 translations and the 3 rotations. The objective of this work is to assess the suitability of machine supported by AMBs to withstand base motions for applications such as compressors on FPSO (Floating production storage and offloading) or emergency steam turbines in nuclear plants. The model developed takes into account the base motion, unbalances on rotor, gravity and bearings properties. The consideration of the base motions has a significant impact on equations of motion and introduces parametric excitations. The centrifugal stiffening effect due to the base rotations is considered. The developed model, is compared with previous experiments performed with a light rotor mounted on classical ball- bearings. The dynamic behavior is analyzed for different types of base motion. Then, the capability of AMB to sustain base motions is examined. Numerical simulations are performed with a rigid rotor supported by two AMBs. The latter are controlled with an augmented PID not specifically tuned for base motion purpose. Finally, the results are discussed. The model developed is a first step for the improvement of turbomachinery supported by AMB. The aim is to eliminate a blocking point to the penetration of AMB technology in on board applications.