Design, Construction, and Modeling of a Flexible Rotor Active Magnetic Bearing Test Rig

A successful industrial application of flexible rotors supported on active magnetic bearings (AMBs) requires careful attention not only to rotordynamic design aspects but also to electromagnetic and feedback control design aspects. Model-based control design provides the framework to ensure efficient, reliable, and safe operation of turbomachinery on AMBs. This paper describes in detail the design, construction, and modeling process for a high performance AMB test rig which typifies a small industrial super-critical centrifugal compressor. A unique aspect of the design are the two additional radial AMBs to allow the application of simulated destabilizing fluid or electromagnetic forces to the rotor. These forces are difficult to predict and can lead to rotordynamic instability of industrial machinery if not properly accounted for. This test rig provides a realistic platform to evaluate stabilizing control algorithms for high performance turbomachinery. A complete model of rotor, AMB actuators and accompanying electronics, is constructed from individually verified component models. Model validation is confirmed through the successful design and implementation of a mu-synthesis controller.