Disk drive optimizing spindle motor torque by adjusting leading phase angle during spin-up
AssigneeWestern Digital Technologies, Inc.
InventorsWenli Yang, Philip Tin Yue Ng, Ashok K. Desai, Robert P. Ryan
Life of this patent
Estimating the term…
Abstract
A disk drive is disclosed comprising a head actuated over a disk, and a spindle motor for rotating the disk, the spindle motor comprising a plurality of windings. During a spin-up operation a sinusoidal driving voltage is applied to each winding of the spindle motor. A back electromotive force (BEMF) voltage generated by at least one of the windings is measured, and a rotation speed of the spindle motor is measured. The sinusoidal driving voltage is adjusted in order to optimize a lead angle relative to the rotation speed, wherein the lead angle represents a degree the sinusoidal driving voltage leads the BEMF voltage.
Claims6
A disk drive comprising:
- a disk;
- a head actuated over the disk;
- a spindle motor for rotating the disk, the spindle motor comprising a plurality of windings;
- and
- control circuitry operable to spin-up the disk by:
- applying a sinusoidal driving voltage to each winding of the spindle motor;
- measuring a back electromotive force (BEMF) voltage generated by at least one of the windings;
- measuring a rotation speed of the spindle motor;
- and
- adjusting the sinusoidal driving voltage in order to optimize a lead angle relative to the rotation speed and a target maximum current applied to at least one of the windings, wherein the lead angle represents a degree the sinusoidal driving voltage leads the BEMF voltage,
- wherein the control circuitry is operable to adjust the sinusoidal driving voltage so that the lead angle is approximately equal to:
- arctan
-
- (
- ω
- e
-
- L
- w
- ×
- I
- max
- K
- e
-
- ω
- +
- R
- w
- ×
- I
- max
- )
- where:
- ω represents the rotation speed of the spindle motor;
- ωe represents an electrical rotation speed of the spindle motor;
- Imax represents the maximum current;
- Ke represents a voltage constant of the spindle motor;
- Lw represents an inductance of at least one of the windings;
- and
- Rw represents a resistance of at least one of the windings.
A method of operating a disk drive, the disk drive comprising a head actuated over a disk, and a spindle motor for rotating the disk, the spindle motor comprising a plurality of windings, the method comprising:
- applying a sinusoidal driving voltage to each winding of the spindle motor;
- measuring a back electromotive force (BEMF) voltage generated by at least one of the windings;
- measuring a rotation speed of the spindle motor;
- adjusting the sinusoidal driving voltage in order to optimize a lead angle relative to the rotation speed and a target maximum current applied to at least one of the windings, wherein the lead angle represents a degree the sinusoidal driving voltage leads the BEMF voltage;
- and
- adjusting the sinusoidal driving voltage so that the lead angle is approximately equal to:
- arctan
-
- (
- ω
- e
-
- L
- w
- ×
- I
- max
- K
- e
-
- ω
- +
- R
- w
- ×
- I
- max
- )
- where:
- ω represents the rotation speed of the spindle motor;
- ωe represents an electrical rotation speed of the spindle motor;
- Imax represents the maximum current;
- Ke represents a voltage constant of the spindle motor;
- Lw represents an inductance of at least one of the windings;
- and
- Rw represents a resistance of at least one of the windings.
Dependencies are inferred from the claim text.