Effect of Manufacturing Errors on the Electromagnetic Vibration of Brushless DC Motors

• Published in: Nihon Kikai Gakkai ronbunshū. C Vol. 19; no. 5; pp. 1346 - 1352
• Main Authors: Yoshikuwa, Yoshio, Imagi, Akihiko, Oikawa, Tomoaki
• Format: Journal Article
• Language: Japanese
• Published: 01.05.2007
• ISSN: 0387-5024

Brushless DC motors, which are widely used in many household electrical appliances, require noise reduction to improve their functionality. Owing to the inevitable manufacturing and assembly errors, the vibration level in actual motors will often exceed the level assumed in design. In order to investigate the generation of electromagnetic vibration, we developed experimental apparatus which can measure the radial force and vibration of the motor. A feature of the experimental apparatus is to preset the amount of eccentricity of the rotor to the stator. We investigated the effect of manufacturing errors on electromagnetic vibration and obtained the following results : when the rotor and the stator are in an eccentric relation, the electromagnetic force is generated in the radial direction. The frequencies of the radial forces are affected by the number of poles, and their levels are proportional to the eccentricity. When the inside of the stator is elliptical, electromagnetic vibration is generated in the second mode. The frequencies of the electromagnetic vibrations are several times the number of poles, and their levels are proportional to the eccentricity and the circularity of the stator.