The present work investigates vibro-acoustic behaviors of the fluid dynamic bearing (FDB) spindle motors for hard disk drives (HDD) through the sound spectra and the frequency response functions (FRF) of the motor structure. The quantitative evidence on the significance of the acoustic noise originated from the electromagnetic source is deduced from the sound spectra that were measured in two distinct cases of the spinning motor: in the normal operation and at the moment immediately after the power supply was disconnected. It is found that the effect of electromagnetic noise source is more dominant than the combined effect of the mechanical and aerodynamic sources. In addition, it is identified that, within the audible range of frequency, the frequency range of 13.4–20 kHz deems important to the noise problem as it is the main contributor to the acoustic noise for the FDB spindle motors. Moreover, the structural resonances that can be identified via the FRF are found to play an important role in the noise emitted by the motors. The concurrence of resonance and excitation frequencies clearly intensifies the sound spectrum, resulting in high discrete peaks, hence higher decibel level.
[1]
Q. Jiang,et al.
Effect of drive modes on the acoustic noise of fluid dynamic bearing spindle motors
,
2003
.
[2]
Timothy J. E. Miller,et al.
Design of Brushless Permanent-Magnet Motors
,
1994
.
[3]
L. R. Quartararo,et al.
Noise and Vibration Control Engineering: Principles and Applications
,
1992
.
[4]
G. Jang,et al.
Torque and unbalanced magnetic force in a rotational unsymmetric brushless DC motors
,
1996
.
[5]
A. Hartman,et al.
Undriven vibrations in brushless DC motors
,
2000,
2000 Asia-Pacific Magnetic Recording Conference. Digests of APMRC2000 on Mechanical and Manufacturing Aspects of HDD (Cat. No.00EX395).
[6]
S. J. Yang,et al.
Low-Noise Electrical Motors
,
1981
.
[7]
Quan Jiang,et al.
Reduction of acoustic noise in FDB spindle motors by using drive technology
,
2003
.