Research On Fractional Modeling And Control Of Active Magnetic Bearings

Active Magnetic Bearings(AMB)use the controlled electromagnetic force generated by an electromagnet to stabilize the suspension of the rotor.There is no mechanical contact between the other components.Compared to conventional mechanical bearings,active magnetic bearings have the unique advantages of high speed,controlled damping and non-contact.and has very broad application prospects.However,the eddy currents generated by the time-varying magnetic field in the active maglev bearing caused by the control current not only lead to power losses in the system.It also leads to phase hysteresis and gain attenuation,which makes the active magnetic bearing system exhibit fractional-order characteristics.In this paper,a fractional-order model of the active magnetic bearing system incorporating the eddy current effect is derived,and based on this model,the active magnetic bearing is systematically A control study to identify and consider the unbalanced vibration of the rotor.The main work of the thesis is as follows.(1)Studied the basic principle of active magnetic bearing system and designed the overall structure of the five-degree-of-freedom active magnetic bearing system.The finite element simulation software is used to analyze the electromagnetic field of the axial and radial magnetic bearings,The electrically controlled part of the magnetic suspension bearing system.(2)Considering the effect of eddy current on the active magnetic suspension bearing,the eddy current fractional order coefficients are proposed and the system is developed with a 2.5 order fractional-order model and the order-variable fractional-order model.(3)System identification of the active magnetic bearing system,and data of each model structure and experimental data using quantum particle swarm algorithm The optimal parameters of each type of model structure are fitted,and by comparing the frequency domain response errors between each optimal model and the experimental data,the frequency domain response errors from the experimental The fractional-order characteristics of the active magnetic bearing are verified at the level of the active magnetic bearing,which also proves the rationality of the fractional-order model proposed in this paper.(4)To address the problem of the influence of rotor unbalance force on the operation of the system,an incomplete differential PID controller is designed to realize the system’s In high-speed operation,it is found that the rotor unbalance vibration is more obvious when the rotor speed is lower.Therefore,in this paper,a multi-frequency trap is designed to suppress the periodic vibration caused by the unbalanced force of the rotor.The maximum displacement of the rotor after 15 HZ is less than that of the protection bearing and rotor.30%of the air gap,meeting the criteria for long-term stable operation..