Experimental Evaluation of a Surge Controller for an AMB Supported Compressor in the Presence of Piping Acoustics

This brief studies the active control of compressor surge using the thrust active magnetic bearing (AMB) in centrifugal compressors and it presents experimental test data to demonstrate the effectiveness of the control solution in industrial size equipment. A detailed step-by-step description is provided from the derivation of the surge model, to the implementation and experimental testing of the surge controller. To accurately represent the configurations found in industrial systems, the proposed surge suppression method is implemented integrally using common off-the-shelf components. During the design of the surge controller, special attention is paid to a possible conflict between the surge controller and the AMB´s internal rotor levitation controller. Observations from the experimental surge testing demonstrate that the presented method is able to stabilize the compression system when operating in the unstable surge region, extending the stable flow range by over 21%. In practice, this allows the compressor to operate at the peak pressure/efficiency point, while maintaining a healthy surge margin as commonly prescribed in industrial compressors.