Synchronous vibration suppression of magnetic bearing systems without angular sensors

Active Magnetic Bearing (AMB) levitates rotor by magnetic force without friction, and it can provide active control force to suppress vibration while rotating. Most of vibration suppressing methods need angular speed sensors to obtain rotating speed, but in many occasions, angular speed sensor is difficult to install or is difficult to guarantee reliability. This paper proposed a vibration suppressing strategy without angular speed sensor based on generalized integrator and frequency locked loop (GI-FLL) and phase shift generalized integrator (PSGI). GI-FLL and high-pass filter estimate frequency from control current, PSGI is applied to generate compensating signal. Firstly, model of AMB system expressed by transfer function is established and effect of centrifugal force is analyzed. Then, principle and process of vibration suppressing strategy is introduced. Influence of parameters are analyzed by root locus and bode diagram. Simulation results display the process of frequency estimation and performance of displacement. Experiments are carried on a test rig, results of simulations and experiments demonstrate the effectiveness of proposed vibration suppressing strategy.