Active Disturbances Rejection Decoupling Control And Vibration Compensation Of AC Hybrid Magnetic Bearings

Magnetic bearings are a kind of novel bearings which make rotor suspend in space by magnetic forces.As magnetic bearings have many advantages of no mechanical contact,no abrasion,no lubricated,long life,low wastage,little noise to the traditional bearings,they are attracting more attention gradually.At present,DC active magnetic bearings(AMBs) are the main objects in the research field of magnetic bearings.But the cost of DC power amplifiers is higher than 3-phase conveners.Supported by National Natural Science Foundation of China(50575099), our team is researching a new structure of magnetic bearings powered by 3-phase conveners, which is called as AC hybrid magnetic bearings(HMBs).Based on the configuration of AC HMBs, this dissertation focuses mainly on applying active disturbances rejection control to the decoupling control and vibration compensation control of AC HMBs.The detail contents are as follows:Firstly,the structure of the electric spindle supported by AC HMBs is described in detail. The flux path is analyzed by using equivalent magnetic circuit,the suspension forces of AC magnetic bearings are deduced.The state equation for five degrees of freedom AC hybrid magnetic bearings is built and the corresponding dynamic parameters are calculated.Secondly,the basic theory of active disturbances rejection control(ADRC) is described. Based on the working principle and mathematic model of axial HMBs,ADRCs for magnetic bearings are designed.The performance of designed control system is simulated with MATLAB software.Thirdly,the active disturbances rejection decoupling control strategy for multivariable coupled systems is proposed,and the active disturbances rejection decoupling control system for 5-DOFs AC HMBs is designed.The simulation block of decoupling control system is given.The experiments of the step response,the start up of rotor,the anti-disturbances and robustness of systems are simulated.Finally,the reasons of rotor vibration are introduced and the rotor dynamic equations are built.Based on tracking differentiators and coordinate transformation,the vibration compensation control strategy of AC HMBs is proposed.Then.the control strategy is verified by experiment simulation.