Investigations On Parametric Stability Of Induction Motor

Induction motor is widely used in the field of mechanical engineering due to the advantages of simple structure,stable performance,economical price,high starting torque.However,vibration and noise can be inevitably induced because of the electromagnetic driving.The effect of the electromagnetic force on the vibration,especially the relationships between the key mechanical,electric and magnetic parameters and the dynamic behaviors need to be examined in order to aid in the vibration and noise reduction.The electromagnetic-mechanical coupled dynamic stability is examined based on a three-phase induction motor.The main content and conclusions include:1.The effect of the rotating electromagnetic force on the stator's stability under the inertial coordinates.A mathematical model is developed by using the energy method,which is solved by using analytical and numerical methods.The unstable boundaries and the corresponding regions are obtained by the multi scale method and numerical calculation.The relationships between the parameters,including the stator flexibility,phase current,tooth pitch,and air-gap width,and the dynamic stability.2.The parametric vibration is examined under the field-synchronous coordinates.The mathematical model is developed by using Hamilton principle,and the closed-form expressions governing the unstable boundaries are obtained.The results imply that the time-variant effect can be eliminated by the field-synchronous coordinates.A equivalent simple model with gyroscopic term is created.The proposed method is verified by the numerical calculation.3.An electromagnetic-mechanical coupled dynamic model of the induction motor with external rotor is bulit up under the field-synchronous coordinates.The influence of the basic parameters on the divergence and flutter instability are studied for the starting and braking modes.The instability regions and response obtained by Floquét theory and Runge-Kutta method are compared to verify the analytical results.This thesis is a part of the National Natural Science Foundation of China(Dynamic Topology Optimization of Rotational Ultrasonic System,Grant No.51175370),and a part of the preliminary research of the National Natural Science Foundation of China(Investigation on dynamic tuning and grouped configuration of cyclically symmetric machinery,Grant No.51675368).The studies provide some new directions and ideas for the dynamic modeling and parameter selection of the rotating structure subjected to traveling load.