Rsearch On Self-sensing Magnetic Bearings With Damper Co-located

The high-speed rotating machinery is more and more used in industrial field.Magnetic bearings is very popular because of long life-time,frictionless property and no lubrication.In many application of magnetic bearings,a need to eliminate discrete position sensors may arise either economic or reliability considerations.Magnetic bearings which estimate the position from the information available in the electromagnet signals are referred to as self-sensing magnetic bearings reduced cost and avoid the above problems.At the same time eddy damping is co-located in the self-sensing bearing,however how to understand this damper is very difficult.So research on self-sensing magnetic bearings with damper co-located has great significance.In this paper,the eddy current damping of the magnetic bearings was studied.Analysis of electromagnetic and mechanical characteristics of magnetic bearings,In order to solve the problem that eddy damping of the magnetic bearing was difficult to understand,and there were too many intermediate links in the self-sensing algorithm,a novel direct current sampling method was proposed.simplified algorithm for the self-sensing of magnetic bearings,as well as quantitative description of the influence of eddy current damping on the magnetic bearings.Firstly,this paper introduced the working principle of the magnetic bearing system.Magnetic flux was used to set up the inductance which contains motional electromotive force,The dynamic mathematical model of single freedom linear magnetic bearing is established,then,magnetic vector was used in building the eddy damper.Secondly,Magnetic bearing model was controlled by differential approach.Based on the derivation high order magnetic bearing mathematical model including vibration velocity,combined with the characteristics of magnetic bearing of the electrical and mechanical parameters,this paper talk about the basic principle of self-sensing,introduced phase and amplitude compensation,then,the paper analyzes the characteristics of the magnetic current under the action of the bilateral symmetrical PWM signal,proposes the sampling strategy of the current and the magnetic bearing's self-sensing algorithm.In addition,the self-sensing magnetic model with current damper trough MATALAB/Simulink was built.Some parameters about the bearing were simulated the self-sensing method and eddy damper.Step and sine input signal was tested during the simulation to explain self-sensing characteristic.Impulse signal revealed effect of eddy damper in the self-sensing bearing.The results show that the proposed method can achieve relatively accurate rotor displacement estimation.And the eddy current damping has the corresponding self-stabilization Characteristics for magnetic bearings.Finally,self-sensing was verified by building the micro displacement platform of magnetic bearings and the damper has been proved by principle of eddy current generation.