Research On Noise Reduction Technology Of Brushless DC Motor

Compared with the traditional brushless DC motor,brushless DC motor has no wear of carbon brush and commutator and arc spark in commutation process,more stable torque output and better noise performance,especially in automobile industry,home appliance industry,power transmission and manufacturing industry.The overall manufacturing technology of domestic brushless motor products has been greatly improved,and brushless motor products have mushroomed,but the noise problem of brushless motor products is still a problem to be solved.In this paper,for the brushless motor cooling fan products,the influence factors of electromagnetic noise of brushless motor and noise optimization measures are explored.The modal analysis of the stator and rotor of brushless motor products is carried out with the help of ANSYS finite element software.Combined with the modal analysis results of the stator and rotor,the vibration displacement and sound power level of the stator surface are solved with the help of finite-length cylindrical radiation model theory.The flow chart of complete analysis of motor noise by finite element software is shown.Through the coupling analysis of Ansoft,Harmonic Response and Harmonic Acoustics in ANSYS,the finite element results of motor air gap magnetic density,radial electromagnetic force,stator vibration displacement and vibration noise are obtained.By analyzing the simulation results and the theoretical model of motor vibration,the value of electromagnetic noise which is similar is obtained,which proves the accuracy of the motor noise research method in the article,which can be used as a basis for noise evaluation in the motor development and design stage.Finally,basing on the basis of motor noise theory and finite element modeling analysis,it is determined to optimize the design of motor vibration noise by changing the matching mode of motor pole slot,replacing motor load and reasonably setting the number of segmented oblique poles.The relative comparative experimental datas and results are given to verify the feasibility of the optimization scheme.It is proved that the 8-poles,12-slots and 3-sections inclined pole scheme can have the most optimal improvement effect on reducing motor noise.