The Noise and Vibration Analysis of BLDC Motor Due to Asymmetrical Permanent-Magnet Overhang Effects

This paper relates to a vibration analysis of brushless dc (BLDC) motors using the asymmetrical $Z$-axis overhang of permanent magnet (PM). In BLDC motor, the asymmetrical $Z$-axis overhang of PM generates $Z$-axis thrust, which leads to $Z$-axis eccentric force by commutated current on the rated load and then the $Z$-axis vibration. The $Z$ -axis thrust ripple, which is the source of $Z$ -axis vibration under commutated current, is analyzed by using 3-D finite element method, and the phenomena of $Z$-axis vibration are analyzed by experimentation.