Suppression of Bow-Induced Disturbances in Rotor–AMB Systems through Channel-Specific LQG Tuning

Abstract

Residual shaft bow in rotor systems supported by active magnetic bearings (AMBs) generates synchronous disturbances, resulting in enlarged rotor orbits and reduced control effectiveness. This study proposes a channel specific Linear Quadratic Gaussian (LQG) tuning strategy to suppress bow-induced vibrations in a megawatt class electrical machine driveline consisting of a quill-shaft coupling. The shaft bow is first identified by analyzing displacement sensor responses with the rotor supported on AMBs at low speed, utilizing the 1X harmonic component from frequency-domain analysis. The extracted bow parameters are then used to adjust the Linear Quadratic Gaussian (LQG) controller gains for individual AMB channels while preserving overall closed-loop stability. A finite element model of the rotor–AMB system is utilized to validate the baseline controller and the modified controller for bow compensation. Experimental validation on test platform demonstrates that the proposed channel-specific tuning approach effectively suppresses the residual vibrations, significantly enhances disturbance rejection, and improves overall rotor dynamic performance.