Power electronics control to reduce hard disk drive acoustics pure tones

Hard Disk Drives are used more and more in environments where the noise level needs to be kept at a very low level. One example is the DVR-application in a bedroom. While the mechanics are important, power electronics control can help to reduce the noise. This paper is presenting two new algorithms that reduce significantly the acoustics pure tones generated by the spindle motor. The first method counters 5/7th harmonics. The second dilutes the pure tones thanks to a spread spectrum approach. Comprehensive theory and measurement data are presented. The electronics driver stays simple and is available into low-cost custom IC.