Dynamic Characteristics Of Active Magnetic Bearing System On Turbine Expander

An active magnetic bearing (AMB) system has been successfully developed for turbine expander by our laboratory. Dynamic characteristics of the system are studied by theoretical analysis and experiment investigation in this paper. The relationships among stiffness, damping, stability, innate frequency and control parameters are discussed. The results show that the scope of the stiffness and damping of the AMBs is limited by the system stability. Both the cylindrical and conical innate frequencies are sensitive to the control parameters, while the first innate bending frequency is less sensitive. On the other hand, the adjustment of the control parameters and the increase of the damping of the AMBs can restrain vibration of the rotor rotating at the cylindrical and conical innate frequencies, while the damping of the AMBs is too little to keep the rotor rotating normally when the rotor operates near the first bending innate frequency.