Study On Resonance Of Rotor-shaft System Model Of Dynamo Forced By Electromagnetic

The motor is a kind of important drives, and with the developing of economy, theapplication of it becomes more and more wide, the structure of motor complicated makesits vibration and other security problems become more and more serious. Therefore,studying motor rotor shaft vibration problems under the action of the air-gap magneticfield magnetic force have theoretical and practical significance.This paper is dedicated to study the regular actions of single resonance and multipleresonances compution research of motor rotor shaft system under the electromagneticforce.First of all, based on the actual structure of the motor, establish a physical model ofmotor rotor shaft system. Research the transverse electromagnetic vibration problems ofthree-phase asynchronous motor rotor shaft symmetric running in the steady-state, themain considerations are air-gap magnetic field electromagnetic force, bearing of theelastic supporting, the rotor with eccentric mass, the mass of the shaft is assigned to therotor averagely and the rotor bearing, considering the gyroscopic effect.Secondly, based on the basic theories of electromagnetism, calculate the potentialenergy and kinetic energy and the air-gap magnetic field between stator and rotor of thethree-phase asynchronous motor rotor shaft system. Analysis the rotor, considering thegyro effect of the rotor, take the linear part of each energy into Lagrange maxwell’sequations, establish linear vibration differential equations, and get the system’s naturalfrequencies and vibration modes. Analyzes the effects of mechanical parameters andelectromagnetic parameters on the natural frequencies. Discusse the motor speed, theinertia, elastic coefficient of the bearing on both ends, the influence of electromagneticstiffness on the natural frequencies, and get regular curves.Finally, introduce energy method and application principle systemly, and apply theenergy method to the analysis of single resonance, double resonances and tripleresonances of the system caused by the corresponding electromagnetic force, and studythe nonlinear vibration problems of the rotor shaft elastic supporting system, aapproximate solution and steady state response curve of the system are obtained. To thesingle resonance, discussed the influence of the damping and electromagnetic force onthe amplitude frequency curve; To the double resonances, as internal resonance isinsufficient detuning, response curves demonstrate soft characteristics; as internal resonance is detuning fully, response curves demonstrate symmetry; as internalresonance is over detuning, response curves demonstrate hard characteristics. Theconclusions of theoretical analysis conform to the experimental results; To tripleresonances question, analysis the influence of damping and electromagnetic parameterson the amplitude frequency characteristics curves, and analyses the harmfulness ofresonance. Researching the reliability design of motor provides some theoreticalreferences.