Unbalanced Magnetic Forces Due to Rotor Eccentricity in a Toroidally Wound BLDC Motor

摘要

A common source of noise and vibrations in a permanent-magnetic synchronous motor is the radial forces due to rotor eccentricity. In this paper, we present entirely analytical models for the radial forces resulting from the eccentricity in a toroidally wound brushless dc motor by applying the perturbation theory. The air-gap magnetic field with eccentricity is first obtained. Then, the radial forces are obtained by integrating the Maxwell stress tensor. The radial force models are verified against the finite-element analysis (FEA). It is found that the maximum mismatch between the results by the model and by FEA is <2%, which confirms the validity of the model.