Study On The Dynamics Of Electromagnetic Bearing-rotor System And The Method Of Nonlinear Control With Variable Parameters

With the rapid development and progress of science and technology,modern industry has increasingly strict requirements on rotating machinery in many aspects such as high speed,high precision,reliability,controllability,high efficiency,and adaptability to complex and harsh environments.Traditional mechanical bearings,due to their own unavoidable mechanical contact,inevitably cause many defects,and they cannot meet the harsh conditions mentioned above.Therefore,the non-contact suspension bearing technology has become a major technical breakthrough.Among them,magnetic levitation bearings-also known as electromagnetic bearings,achieve the suspension of the rotor by generating a controlled non-contact magnetic field force,avoiding the contact between the rotor and the bearing,thus having no friction(small vibration noise)and no wear(energy Low consumption),no lubrication(no pollution),controllable(high reliability and high precision),long service life and long-term maintenance-free and many other advantages.However,there are still many factors,for example: when the rotor rotates at high speed,the overall dynamic properties of the bearing rotor system are not stable;the material properties and structural design of the electromagnetic bearing are relatively complicated;Reaching the ideal level and the high cost of electromagnetic bearings have all restricted the popularity of electromagnetic bearings in China's industrial equipment.Therefore,at present,there is an urgent need to carry out in-depth research on electromagnetic bearing technology in order to provide technical reserves for the next industrial upgrade.This paper has carried out theoretical exploration and simulation analysis of the electromagnetic bearing rotor system.The main research work is as follows:First,the linear and various nonlinear forms of electromagnetic force in the electromagnetic bearing are derived,and the dynamic equations of the electromagnetic bearing rotor system are established.Subsequently,referring to the existing commercial electromagnetic bearing structural design software,I developed a set of electromagnetic bearing design schemes,and realized the parameterized design of the electromagnetic bearing structure by writing a program.In addition,a new variable-parameter nonlinear PID control strategy is designed in order to achieve a better control effect.Finally,the finite element analysis software ANSYS was used to analyze the rotor dynamics of the electromagnetic bearing rotor system designed by ourselves.Through the simulation results of various control algorithms,it can be seen that the new improved PID control algorithm proposed in this paper has an order of magnitude improvement in control effect compared with the original control method.Through the dynamic analysis of the rotor of ANSYS,it is shown that the designed electromagnetic bearing rotor system meets the requirements of various API protocols.