Data storage device detecting spindle motor position at increased resolution using mutual inductive sense

Patent metadata

Field	Value
Publication number	US-10242706-B1
Application number	US-201815965947-A
Country	US
Kind code	B1
Filing date	Apr 29, 2018
Priority date	Apr 29, 2018
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk. A first driving voltage is applied across a first and second windings of the spindle motor connected in series while measuring a first mutual inductance voltage across a third winding, wherein the first driving voltage comprises a first amplitude and a first polarity. A second driving voltage is applied across the first and second winding connected in series while measuring a second mutual inductance voltage across the third winding, wherein the second driving voltage comprises the first amplitude and a second polarity opposite the first polarity. The first measured mutual inductance voltage and the second measured mutual inductance voltage are combined to generate a first mutual inductance signal, and an angular position of the spindle motor is estimated based on the first mutual inductance signal.

First claim

What is claimed is:

1. A data storage device comprising:
a disk;
a head actuated over the disk;
a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings including a first, second and third winding; and
control circuitry configured to:
apply a first driving voltage across the first and second windings connected in series while measuring a first mutual inductance voltage across the third winding, wherein the first driving voltage comprises a first amplitude and a first polarity;
apply a second driving voltage across the first and second windings connected in series while measuring a second mutual inductance voltage across the third winding, wherein the second driving voltage comprises the first amplitude and a second polarity opposite the first polarity;
combine the first measured mutual inductance voltage and the second measured mutual inductance voltage to generate a first mutual inductance signal; and
estimate an angular position of the spindle motor based on the first mutual inductance signal.

2. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to generate the first mutual inductance signal by adding the first measured mutual inductance voltage and the second measured mutual inductance voltage.

3. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to estimate the angular position of the spindle motor based on a zero crossing of the first mutual inductance signal.

4. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to:
apply the first driving voltage across the second and third windings connected in series while measuring a third mutual inductance voltage across the first winding;
apply the second driving voltage across the second and third windings connected in series while measuring a fourth mutual inductance voltage across the first winding;
combine the third measured mutual inductance voltage and the fourth measured mutual inductance voltage to generate a second mutual inductance signal; and
estimate an angular position of the spindle motor based on the first mutual inductance signal and the second mutual inductance signal.

5. The data storage device as recited in claim 4 , wherein the control circuitry is further configured to generate the second mutual inductance signal by adding the third measured mutual inductance voltage and the fourth measured mutual inductance voltage.

6. The data storage device as recited in claim 4 , wherein the control circuitry is further configured to estimate the angular position of the spindle motor based on a mutual crossing of the first mutual inductance signal with the second mutual inductance signal.

7. The data storage device as recited in claim 6 , wherein the control circuitry is further configured to estimate the angular position of the spindle motor based on a zero crossing of the first mutual inductance signal and a zero crossing of the second mutual inductance signal.

8. The data storage device as recited in claim 7 , wherein the mutual crossing is separated from the zero crossing of the first mutual inductance signal by approximately thirty electrical degrees of the spindle motor.

9. A data storage device comprising:
a disk;
a head actuated over the disk;
a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings including a first, second and third winding; and
control circuitry configured to:
apply a first driving voltage across the first and second windings connected in series while measuring a first mutual inductance voltage across the third winding;
apply a second driving voltage across the first and second windings connected in series while measuring a second mutual inductance voltage across the third winding;
combine the first measured mutual inductance voltage and the second measured mutual inductance voltage to generate a first mutual inductance signal;
apply the first driving voltage across the second and third windings connected in series while measuring a third mutual inductance voltage across the first winding;
apply the second driving voltage across the second and third windings connected in series while measuring a fourth mutual inductance voltage across the first winding;
combine the third measured mutual inductance voltage and the fourth measured mutual inductance voltage to generate a second mutual inductance signal; and
estimate an angular position of the spindle motor based on a zero crossing of the first mutual inductance signal, a zero crossing of the second mutual inductance signal, and a mutual crossing of the first mutual inductance signal with the second mutual inductance signal.

10. The data storage device as recited in claim 9 , wherein the mutual crossing is separated from the zero crossing of the first mutual inductance signal by approximately thirty electrical degrees of the spindle motor.

11. A method of operating a data storage device, the method comprising:
connecting in series a first winding and a second winding of a spindle motor configured to rotate a disk;
applying a first driving voltage across the first and second windings connected in series while measuring a first mutual inductance voltage across a third winding of the spindle motor, wherein the first driving voltage comprises a first amplitude and a first polarity;
applying a second driving voltage across the first and second windings connected in series while measuring a second mutual inductance voltage across the third winding, wherein the second driving voltage comprises the first amplitude and a second polarity opposite the first polarity;
combining the first measured mutual inductance voltage and the second measured mutual inductance voltage to generate a first mutual inductance signal; and
estimating an angular position of the spindle motor based on the first mutual inductance signal.

12. The method as recited in claim 11 , further comprising generating the first mutual inductance signal by adding the first measured mutual inductance voltage and the second measured mutual inductance voltage.

13. The method as recited in claim 11 , further comprising estimating the angular position of the spindle motor based on a zero crossing of the first mutual inductance signal.

14. The method as recited in claim 11 , further comprising:
applying the first driving voltage across the second and third windings connected in series while measuring a third mutual inductance voltage across the first winding;
applying the second driving voltage across the second and third windings connected in series while measuring a fourth mutual inductance voltage across the first winding;
combining the third measured mutual inductance voltage and the fourth measured mutual inductance voltage to generate a second mutual inductance signal; and
estimating an angular position of the spindle motor based on the first mutual inductance signal and the second mutual inductance signal.

15. The method as recited in claim 14 , further comprising generating the second mutual inductance signal by adding the third measured mutual inductance voltage and the fourth measured mutual inductance voltage.

16. The method as recited in claim 14 , further comprising estimating the angular position of the spindle motor based on a mutual crossing of the first mutual inductance signal with the second mutual inductance signal.

17. The method as recited in claim 16 , further comprising estimating the angular pos

Assignees

• Western Digital Tech Inc

Inventors

• Johnson Brian A
• Ferris Timothy A
• Byoun Jaesoo

Classifications

• H02P6/185

  using inductance sensing, e.g. pulse excitation · CPC title

• G11B19/2009 Primary

  Turntables, hubs and motors for disk drives; Mounting of motors in the drive (means for clamping of disk to turntable G11B17/022 and subgroups) · CPC title

• G11B19/02

  Control of operating function, e.g. switching from recording to reproducing · CPC title

• H02P6/182

  using back-emf in windings · CPC title

• H02P25/034

  Voice coil motors (voice coil motors driven by DC H02P7/025) · CPC title