Random modulation and acoustic noise reduction in IM drives: a case study

The actual and general trend in the reduction of environmental noise pollution represents a new challenge for motor and drive designers. As in every initial stage, the goal is clear but the methods of comparison and measurement are still fuzzy. The paper presents the detailed acoustic characterisation of a simple variable speed drive, constituted by an induction motor (IM) fed by a voltage inverter. By the considered case study, the work emphasises the manifold items that contribute to the noise characterisation, and it gives some design hints to minimise the related human hearing annoyance