Analysis of acoustic noise sources of FDB and ADB spindle motors operating at BLDC mode

The electromagnetic (EM) sources of the acoustic noise are very concerned in the spindle motor used in the hard disk drives (HDDs). Identifying the effects of these sources is important for high performance hard disk drive products. The electromagnetic analysis results in this paper show that, when the spindle motor is driven by brushless DC (BLDC) mode, the EM torque ripples can be categorized as intrinsic BLDC torque ripple and commutation torque ripple. A set of experiments were designed, tested and analyzed for identifying the effects of these ripples, and the results showed that the commutation torque ripple is the dominant EM source of the acoustic noise.