The vibration and noise of motors can be classified into three categories: electromagnetic, mechanical and comprehensive reasons.
The cause of electromagnetic failure is that the fault will disappear immediately after power failure.
Mechanical causes are closely related to the rotating speed of the motor. As long as the problem of rotating state is more or less, the more and less the general speed is, the more and more the speed is, the resonance and howling of individual at a certain speed will occur.
The most common causes are electromagnetic force and mechanical polarization. Sometimes there is a superposition effect.