Active Magnetic Bearings for Fault Detection in a Centrifugal Pump

Active magnetic bearings (AMB), a typical mechatronic product, have been successfully applied in industrial turbomachinery. They are well suited to operate contactless as actuator and sensor elements in rotating machinery. The aim of the presented projects of the Special Research Program (SFB 241) supported by the German Research Council (DFG) is to use active magnetic bearings as an identification and diagnosis tool for turbomachines. The identification and diagnosis procedures are based on frequency response functions. For this type of diagnosis using transfer functions, an accurate force measurement as well as a precise model are crucial. The paper compares force measurement results and achievable accuracies of radial and axial magnetic bearings using different measurement techniques over a large operating range.