Internal Vibration Source Analysis of AMB-Rotor System in HTR-PM Primary Helium Circulator

The active magnetic bearing (AMB) in HTR-PM primary helium circulator (PHC) applies the inductive displacement transducer (IDT) to achieve the closed-loop feedback control. The magnetic anisotropy of the rotor material can be equivalent to structure defect of the rotor and affect the IDT measurement accuracy, leading to internal exciting vibration of the rotor. In this paper, the magnetic field analysis shows that the rotor magnetic anisotropy has effect on the sensor measurement and brings about the displacement measurement error. In the rotor-sensor experiment, the effect of rotor magnetic anisotropy on the IDT is obtained as a curve of magnetic error, which further explains that the rotor magnetic anisotropy will affect the dynamic measurement accuracy of the IDT. With the simulation result, it is observed that the displacement measurement error will lead to the internal exciting force of AMB-rotor system. The force will increase as the rotor speed increases, and bring about high-frequency vibration of the rotor.