Noise source identification of a BLDC motor

This paper proposes an analysis procedure of brushless DC(BLDC) motor noise. A systematic approach for identification of noise sources is suggested considering electromagnetic forces, structural and acoustic modes. It is proved by finite element analysis and experiments that the electromagnetic forces and the structural modes are not the major noise source since the noise characteristics are not closely related to the motor RPM. Acoustic modal analysis and tests reveal that the acoustic mode of the internal airspace of the motor is the major noise source.