Research On Electromagnetic Vibration And Noise Suppression Of Induction Motor For Electric Vehicle

The low noise of electric drive is come to be one of the most important indexes of electric vehicle industry along with the emphasis on comfort and electric drive noise.The use of induction motor as an electric drive system for electric vehicles has the advantage of high reliability,easy maintenance,low cost,and has been widely used.Electric drive noise comes mainly from the electromagnetic vibration and noise of the induction motor,so reducing the electromagnetic vibration and noise of the induction motor has important practical value and theoretical significance.Induction motor is driven by the inverter,electromagnetic design of the motor and the control strategy of the inverter are the key factors which determine the electromagnetic vibration and noise of the induction motor.This paper focuses on these two aspects,make deep studies on the theory of electromagnetic vibration,noise and engineering practically research of induction motor.This paper describes the theory of electromagnetic vibration and noise in induction motor,analyzes the influence of air gap magnetic flux distribution by using the product of magnetic potential and magnetic permeance,study the correlation between radial electromagnetic force wave and electromagnetic vibration and noise.The whole modal including stator winding,end cap,bearing and rotor structure is analyzed by finite element method,vibration mode and natural frequency of the motor are obtained,laying the theory foundation for the analysis of motor electromagnetic vibration and noise.This paper aimed on reducing low-order radial electromagnetic force wave and reducing the amplitude of electromagnetic force.Study the method of avoiding the resonance and reducing electromagnetic vibration and noise of the induction motor used by electric vehicle.Under the premise of ensuring the maximum torque and efficiency of the motor,optimize the slot number of the rotor and the skew distance of the rotor bar,weaken the electromagnetic vibration and noise of the induction motor.Using Ansoft/Maxwell build simulation model to verify the correctness of the optimization results.In this paper,a random switching frequency pulse width modulation control strategy is adopted to make the current frequency spectrum characteristics become even,so as to weaken the motor electromagnetic vibration and noise.Build an effective simulation model in Matlab/Simulink platform to verify the effectiveness of this control strategy,and the power spectral density of the output current of the inverter at fixed switching frequency and random switching frequency was analyzed and compared.The effectiveness of the random switching frequency control strategy was verified by simulation.The simulation results prove that the control strategy has a good effect on making the current frequency spectrum characteristics become even.This paper elaborates the effectiveness of the optimization method and manufactures prototypes based on this.The accelerometer is used to measure and compare the vibration data before and after rotor optimization.The correctness of the above electromagnetic vibration and noise optimization method is proved and the noise performance of the product is greatly improved.By analyzing the data of the inverter current and the motor vibration data from the towing platform,the proposed control strategy's feasibility and effectiveness on suppression of electromagnetic vibration and noise are proved.