Investigation of the feasibility of active balancing of hard disk drives

Abstract

Vibrations are one of the major factors limiting the increase of the storage density of hard disk drives. One of the sources of the vibrations is the unbalance caused by an uneven distribution of the mass on the rotational part of the hard disk drive. This technical note proposes a new method for the reduction of unbalance-induced vibrations. Vibration reduction is achieved by the so-called active balancing technique which represents a new approach as compared with traditional passive balancing methods. The proposed method is using injection of current into the existing windings of an asymmetric spindle motor in order to generate an electromagnetic force which acts against the centrifugal force caused by the unbalance. Advantages and disadvantages of this method are analyzed and discussed.