Surge Detection of AMB-Supported Centrifugal Compressors Using a Normalized Adaptive Notch Filter

Surge is an aerodynamic instability state suffered by centrifugal compressors, which can lead to severe performance degradation and extensive structural damage. Therefore, mild surge detection is an essential technology for machine safety and efficiency. This paper proposes a novel surge detection scheme for magnetically suspended centrifugal compressors (MSCCs) by utilizing the condition monitoring capability of active magnetic bearings (AMBs). First, a surge disturbance transfer model is established based on the correspondence between surge characteristics and bearing vibration force. Then, synchronous rotating frame (SRF) transformation, known for its outstanding convergence performance, is employed to eliminate synchronous vibrations in the bearing force. A normalized adaptive notch filter (ANF) is designed, which can accurately extract the surge fundamental component even in the presence of dc offset and surge harmonic in the bearing force. The convergence of the modified ANF is not affected by surge frequency and amplitude. Furthermore, a judgment criterion for surge detection is established based on the estimated signal. Finally, experimental results indicate that the proposed method allows for higher estimation accuracy and rapid detection of mild surge over the entire speed range.