The Analysis Of Harmonic In Inverter- Driven Induction Motors

Variable voltage speed regulation technology makes induction motors have better starting performance compared with the traditional motor,but a large amount of harmonic components which affect the performance of the motor are generated inside the induction motor at the same time.This makes the analysis of the reasons of how harmonics occur in the induction motor and the study about the influence of harmonics on the performance of the motor in different situations become very valuable.This dissertation analyses the causes and derives the formulas of time harmonics and space harmonics in induction motors,and explains the effects and harms of time harmonics and space harmonics on induction motors.After extracting the air gap magnetic density of induction motors,this dissertation compares the harmonic components of the air gap magnetic density in different working conditions and different power supply,and the variation of the harmonic components is obtained at the same time.The frequency conversion induction motor needs to work at different power points,due to different working environments and working conditions.Therefore,this dissertation has done the analysis about the performances of the variable frequency motor basing on the model of inverter-driven induction motor,and obtained the changing rules of phase voltage,copper loss,iron loss,efficiency and power factor of induction motor at different power points.Compared with the conventional power driven motor,the harmonic content of the input voltage in inverter-driven motor is very rich.This dissertation simulates the induction motor when it is powered by different power supplies,and the changing rules of some performance parameters of the induction motor are obtained.In this dissertation,basing on the experimental and simulation results,the data obtained through the two ways are compared and analyzed,and the correctness of the research has been verified.