Tangential force effect on the vibration and noise of PMDC motor

For round square PM motor, the tangential force is the main cause of electromagnetic vibration and noise besides radial force, for its geometry structure and electromagnetic characteristic. This paper deduces the round square motor electromagnetic vibration and acoustic radiation formula, then make radial/tangential force and harmonic analysis, by using Finite Element Method (FEA) analysis, indicating that radial force is the main driving source of first order mode for round square motor, and tangential force is the main one of the second order mode. This conclusion is validated by the experimental results of motor noise, The study provides theoretical basis to round square PM motor noise analysis.