Experimental identification and reduction of acoustic noise in small brushed DC motors

Starting from an accurate experimental test campaign to identify the acoustic noise sources in small brushed DC motors for radiator cooling applications, the authors discuss and propose some alternative production solutions of electrical machines able to mitigate the problem. The feasibility of the proposed solution is compatible with the competitive automotive component market and the actual automatic production lines. Several prototypes have been manufactured and tested in the same semi-anechoic chamber as like as the original motor set. The reported noise measurements prove that for the considered application the noise emissions can be reduced to acceptable levels.