| With the development of power electronic technology and modern control theory, AC speed regulating technique has been developing rapidly, and variable-frequency regulating speed technology has been widely used in various industrial fields for its excellent performance. When the motor is fed by variable-frequency power source, the input current of motor winding filled with a series of harmonics instead of a standard sine wave. These harmonics make the air-gap magnetic field more complex, which influence the electromagnetic force of motor and then affect the vibration of motor. In this paper, electromagnetic vibration of motor fed with frequency converter is studied specifically, of which the contents include several parts as following:Firstly, finite element analysis method and approximate analytical calculation method are used to analysis the electromagnetic force of motor fed with frequency converter. The analytical calculation expression of the electromagnetic force is derived. Field-circuit coupled time-stepping finite element model is established. The electromagnetic force is simulated and analyzed. The electromagnetic force spectrums under sine power supply and frequency conversion power supply are contrasted, and the effect of inverter power supply to electromagnetic force is summarized.Secondly, the structural vibration of motor is calculated. The modal analysis of the motor is simulated and analyzed. The vibration mode and natural frequency of the motor are obtained. The modal experiment is performed to verify the accuracy of simulation calculation, which lays the foundation for the later electromagnetic vibration calculation and vibration experimental analysis. The calculated electromagnetic forces are exerted to the stator tooth surface as load. The deformation and vibration acceleration of the motor under different power supply conditions are calculated. Through the analysis of simulation results, the influence of variable frequency power supply to motor vibration is obtained.Finally, vibration experiment is carried out on the prototype. The exciting force sources causing motor vibration are identified by comparing vibration acceleration spectrum under different operating conditions. Experimental results and computational results are compared, and the accuracy of electromagnetic vibration simulation calculation method is verified. The influence of different carrier frequencies and different control strategy to the motor vibration supplied by variable frequency power is compared and analyzed. |
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