| With the rapid development of power electronics technology,the variable frequency drive mode of induction motor is widely used in industrial application due to its excellent speed regulation performance.However,converter may introduce a mass of harmonics in supply,and its interaction with the original time-space harmonics in motors can produce high-frequency radial electromagnetic force,which further affect the vibration characteristics of the motor.This thesis mainly focuses on vibration characteristics of inverter-fed induction motors,and the main works are as follows:1)With sinusoidal and inverter-fed supply,analytical expressions of air-gap flux density of induction motor are derived.With a 5.5 kW induction motor installed test coil in stator slots,the characteristics of electromagnetic force(EMF)induced in the test coil under sinusoidal and inverter-fed supply are measured systematically,and the distribution characteristics of typical time-space harmonics are obtained.2)Expressions of radial electromagnetic force under sinusoidal and inverter-fed supply are derived,and the low-order radial electromagnetic force produced by high frequency harmonics of inverter-fed supply is analyzed.Finite element analysis is also carried out to verify the correctness of the theoretical analysis.3)Modal analysis is carried out for a 55kW inverter-fed induction motor.The transient dynamic analysis and harmonic response analysis are carried out under sinusoidal and inverter-fed supply,and the simulation results are analyzed theoretically.Further,the vibration characteristics under sinusoidal and inverter-fed supply are studied experimentally,the variation characteristics of motor vibration with inverter-fed supply are obtained and the correctness of the theoretical analysis is also verified. |
