The Recognition And Suppression Of Permanent Magnet Synchronous Motors’Electromagnetic Vibration And Noise

The electromagnetic vibration and noise(EVAN)generated by permanent magnet synchronous motors(PMSM)can be reduced in the initial stage of motor design by deeply researching the mechanism and sources of producing them,which will have an important practical significance for improving the comprehensive performance of PMSM,reducing development cycle and environmental protection.In this paper,the characteristics of radial air-gap magnetic density,radial electromagnetic force waves(REFW)and EVAN of PMSM were deeply studied,the specific contents included the following aspects:Firstly,the radial air-gap magnetic density and REFW were deduced by analytical method based on related electromagnetic field theory,obtaining the analytical expressions of amplitudes,spatial orders and frequencies of radial air-gap magnetic and REFW.Combined with the finite element simulation,the main components of REFW which played an important role in producing EVAN were found out through further analysis,and their spatial orders,frequencies and sources were summarized,which laid a foundation for the identification and suppression of the EVAN of PMSM.Secondly,the natural mode of vibration of motors’ stator system were studied by analytical method and finite element method(FEM),the influences of motor housing,end cover and winding on natural frequencies of stator system were emphatically analyzed.It found out that there was a big error between the analytical results and actual results,because the analytical calculation model of stator natural frequency was too simplified,so in order to improve the computational accuracy,the analytical results should be amended.By improving the accuracy of prediction for the natural frequency of stator system and avoiding the resonance,the EVAN of PMSM could be effectively suppressed.Then,the EVAN of PMSM were calculated by analytical method and FEM separately,their characteristics were researched and the accuracy of the analytical calculation results were verified by vibration and noise testing experiment.The influences of amplitudes,spatial orders and frequencies of REFW on EVAN of PMSM were researched,it found out that the REFW with low spatial order and close frequency to the stator system’s inherent frequency were the main factor causing the EVAN of PMSM,which should be weakened emphatically in the process of the suppression of EVAN.Finally,the computational and analytical software of EVAN of PMSM was written,which could be used to fast calculate and recognize the EVAN of PMSM,the accuracy of the system was verified by relevant experiment.Taking a 70 w PMSM as an example,the steps and methods to suppress the EVAN of PMSM from the design perspective and how to recognize the EVAN of PMSM caused by eccentric fault were studied.