Electromagnetic Vibration and Noise Suppression of Induction Motor Based on RPWM Selective Spectrum Shaping

In AC motor powered by frequency converter, the random pulse width modulation (RPWM) can suppress vibration and noise power near the switching frequency and its integer multiple of the inverter. However, the traditional RPWM strategy cannot selectively eliminate the special frequency harmonics, such as the frequency that causes strong electromagnetic vibration and noise of the motor. A method of suppressing electromagnetic vibration and noise of induction motor based on RPWM selective spectrum shaping is proposed. Firstly, according to three different pulse positions, the general formula of selective harmonic elimination of RPWM is derived, so as to selectively eliminate the harmonic noise power at a specific frequency and its integer multiple. On this basis, further spectrum shaping can be realized by reasonably selecting the effective random number to avoid the inverter switching frequency distributing in a specific frequency band. The simulation and experimental results show that the method can not only suppress the vibration and noise near the integer times of the switching frequency, but also selectively suppress the electromagnetic vibration and noise at other frequencies.