The origin of acoustic noise in variable-reluctance motors

The authors study the origin of acoustic noise in inverter-driven variable reluctance motors (VRMs). A brief discussion of several hypothetical noise sources is given. These sources are investigated by performing a series of stationary and rotational experiments on a 1/2 hp VRM. The experiments show that resonant vibrations of the stator induced by radial magnetic forces in the motor are responsible for most of the acoustic noise. A method for predicting the stator´s resonant frequencies and mode shapes is outlined and evaluated. A model of the VRM for predicting the radial acceleration of the stator is presented. Preliminary results from this model are presented.<>