Apparatus and method compensating mechanical tolerance of brushless direct current motor and related disk drive

A method of compensating for a mechanical tolerance of a motor, the method comprising:

• generating a plurality of motor control input signals using a back electromotive force generated by the motor, wherein each rotational period for the motor is divided into a plurality of control sections, and a motor control input signal is generated in each one of the plurality of control sections;
• calculating a moving average value of the motor control input signals over a moving average section including recently generated motor control input signals whenever the motor control input signal is generated;
• and
• driving the motor using an electric current corresponding to the moving average value to compensate for the mechanical tolerance of the motor.

A hard disk drive (HDD) comprising:

• a disk storing data;
• a spindle motor rotating the disk and generating a back electromotive force;
• a spindle motor speed controller calculating a speed difference between a measured motor speed in each one of a plurality of control sections using the back electromotive force generated by the spindle motor and a reference speed, and generating a plurality of spindle motor control input signals in relation to the speed error,
• wherein the plurality of control sections are defined within a single rotational period of the motor;
• a moving average calculator calculating a moving average value of the plurality of spindle motor control input signals over a moving average section including recently generated spindle motor control input signals whenever the spindle motor control input signal is generated;
• and
• a spindle motor driver generating a driving motor current corresponding to the moving average value to compensate for the mechanical tolerance of the motor.