The Analysis And Experimental Study For The Mechanical And Magnetic Coupling Excitation Force In Induction Motor With Static Eccentric Rotor

As the main noise source in large and medium-sized induction motor,the electromagnetic noise is caused by vibration and sound radiation of rotor and stator,which is motivated by air-gap radial electromagnetic force.With the constant development of power,speed and torque output of induction motor during daily life and work,the electromagnetic vibration and noise are becoming worsening problems.The calculation of electromagnetic force is vital to the analysis of motor structure,as well as vibration and noise reduction.At present,the computing methods are still confined to the electromagnetics,for the lack of the mechanical and magnetic coupling analysis.In order to analyze the interaction between rotor vibration and air-gap field in a working induction motor,and predict the asymmetric radial electromagnetic force precisely,a mechanical and magnetic coupling model was set up.Based on the Langrange-Maxwell equation,the numerical solution to the rotor vibration response was obtained,and then electromagnetic force wave was calculated according to the rotor vibration eccentricity.At last,the impact of rotor-shaft system flexural rigidity and initial static eccentricity on the air-gap field and electromagnetic force was analyzed.The accuracy of theoretical modeling and numerical calculation was validated using experimental study.The results show that air-gap field changes because of rotor vibration response in eccentric induction motor.The smaller flexural rigidity and larger the initial static eccentricity is,the more unevenly air-gap field distributes,as a result,the asymmetric radial electromagnetic force on the stator becomes bigger.In conclusion,the theoretical model and numerical solution raised up can provide an accurate calculation for the asymmetric electromagnetic force,especially for motors with elongated shafts.