Disk drive employing spindle motor commutation time variation for reducing acoustic noise

摘要

A disk drive incidentally generates undesirable acoustic noise during an operation mode and includes a spindle motor having windings and a rotor rotatable at an operating spin-rate during the operation mode. A commutation state sequencer includes a sequence of commutation states including a present commutation state and a next commutation state for generating a sequence of control signals. Switching elements are responsive to the sequence of control signals for sequentially applying a voltage across a selected combination of the windings to generate a torque on the rotor in order to maintain the operating spin-rate. A spindle motor control system provides a series of commutation clock pulses having a corresponding series of commutation clock periods to advance the commutation state sequencer from the present commutation state to the next commutation state. At least two of the commutation clock periods each have a systematically introduced variation from a nominal commutation clock period that depends on the operating spin-rate. The systematically introduced variation reduces the acoustic noise in the disk drive.