Experimental Identification and Reduction of Acoustic Noise in Small Brushed DC Motors

The smart actuators and components designed for automotive applications have to satisfy the standards and specifications of costumers, who are becoming more and more demanding, concerning the acoustic-noise emissions. Starting from an accurate experimental test campaign, which identifies the cogging torque as the main cause of the acoustic-noise source in the considered small brushed dc motors for radiator cooling fan applications, the authors discuss and propose some alternative redesign solutions of the electrical machine that are able to mitigate the problem. The feasibilities of the proposed solutions are 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 similar to the originalmotor set in order to comparatively evaluate the goodness of the potential electrical machine redesigns in terms of acoustic-noise reduction. The reported acoustic-noise measurements prove that, for the considered application, the acoustic-noise emissions can be reduced.