The noise of an automotive alternator is composed of mechanical noise, aerodynamic noise and magnetic noise, etc. Other previous studies showed that magnetic noise had a major peak value at the frequency which has the value of rotating frequency multiplied by the number of stator slots. But the fact that the noise of the frequency which has a value of the rotating frequency multiplied by the number of stator slots is mainly caused by stator slots has not been proved clearly. Furthermore, it was well known that rotor slots mainly caused the noise of motor, which has a structure similar to an alternator and the number of stator slots is integer multiple of that of rotor segments in an automotive alternator. Therefore it is difficult to say that stator slots cause the noise of the frequency which has the value of rotating frequency multiplied by the number of stator slots only.
In this paper, through changing the number of stator slots and comparing the noise properties of the pre-modified stator with that of the post-modified stator, we analyzed the effect of stator slots on noise and that of the relationship between the number of rotor segments and that of stator slots on the noise in an automotive alternator
