Data storage device regulating BEMF power voltage during power failure

• US 10,242,698 B1
• Filed: 04/19/2018
• Issued: 03/26/2019
• Est. Priority Date: 04/19/2018
• Status: Active Grant

• Current Assignee: JP Morgan Chase Bank, N.A. (JP Morgan Chase & Co)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Byoun, Jaesoo, Johnson, Brian A., Ferris, Timothy A.
• Primary Examiner(s): Agustin, Peter Vincent
• Application Number:
  US15/956,990
• Time in Patent Office: 341 Days
• Field of Search: None
• CPC Class Codes: G11B 19/2054 Spindle motor power-up sequences
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/33 Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing onlySingle head using magnetic domains for scanning G11B5/4946; multiple head for scanning G11B5/4907 and subgroups ; general details therefor G11B5/133 - G11B5/255
• CPC Class Codes: G11B 5/40 Protective measures on heads, e.g. against excessive temperature G11B5/31 takes precedence; protection against wear G11B5/255 ; protective structure of the head: see under structures, e.g. G11B5/3106
• CPC Class Codes: G11B 5/54 with provision for moving the head into or out of its operative position or across tracks
• CPC Class Codes: G11B 5/82 Disk carriers

Abstract

A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings. During a power failure the head is unloaded by generating a periodic signal, shorting the windings of the spindle motor based on the periodic signal in order to generate a power voltage, and adjusting the periodic signal based on an amplitude of the power voltage.

Claims

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; and

control circuitry configured to unload the head during a power failure by at least;

generating a periodic signal;

shorting the windings of the spindle motor based on the periodic signal in order to generate a power voltage;

measuring an amplitude of the power voltage during at least part of the unload; and

adjusting the periodic signal based on the measured amplitude of the power voltage.

2. The data storage device as recited in claim 1, wherein the periodic signal comprises a square wave.

3. The data storage device as recited in claim 2, wherein the control circuitry is further configured to adjust the periodic signal by adjusting a duty cycle of the periodic signal.

4. The data storage device as recited in claim 3, wherein the control circuitry is further configured to adjust the periodic signal by increasing the duty cycle of the periodic signal as the measured amplitude of the power voltage decreases.

5. The data storage device as recited in claim 2, wherein the control circuitry is further configured to adjust the periodic signal by adjusting a period of the periodic signal.

6. The data storage device as recited in claim 2, wherein the control circuitry is further configured to adjust the periodic signal by decreasing the period of the periodic signal as the measured amplitude of the power voltage decreases.

7. The data storage device as recited in claim 1, wherein the control circuitry is further configured to first adjust the periodic signal when the measured amplitude of the power voltage falls below a first threshold.

8. The data storage device as recited in claim 7, wherein the control circuitry is further configured to second adjust the periodic signal when the measured amplitude of the power voltage falls below a second threshold lower than the first threshold.

9. The data storage device as recited in claim 7, wherein the control circuitry is further configured to:

generate a regulated voltage based on the power voltage; and

generate the first threshold based on the regulated voltage.

10. A method of operating a data storage device, the method comprising:

unloading a head actuated over a disk during a power failure by at least;

generating a periodic signal;

shorting windings of a spindle motor based on the periodic signal in order to generate a power voltage, wherein the spindle motor is configured to rotate the disk;

measuring an amplitude of the power voltage during at least part of the unload; and

adjusting the periodic signal based on the measured amplitude of the power voltage.

11. The method as recited in claim 10, wherein the periodic signal comprises a square wave.

12. The method as recited in claim 11, wherein adjusting the periodic signal comprises adjusting a duty cycle of the periodic signal.

13. The method as recited in claim 12, wherein adjusting the periodic signal comprises increasing the duty cycle of the periodic signal as the measured amplitude of the power voltage decreases.

14. The method as recited in claim 11, wherein adjusting the periodic signal comprises adjusting a period of the periodic signal.

15. The method as recited in claim 11, wherein adjusting the periodic signal comprises decreasing the period of the periodic signal as the measured amplitude of the power voltage decreases.

16. The method as recited in claim 10, further comprising first adjusting the periodic signal when the measured amplitude of the power voltage falls below a first threshold.

17. The method as recited in claim 16, further comprising second adjusting the periodic signal when the measured amplitude of the power voltage falls below a second threshold lower than the first threshold.

18. The method as recited in claim 16, further comprising:

generating a regulated voltage based on the power voltage; and

generating the first threshold based on the regulated voltage.

19. A device comprising:

an electric motor comprising a plurality of windings configured to rotate the electric motor; and

control circuitry configured to;

generate a periodic signal;

short the windings of the electric motor based on the periodic signal in order to generate a power voltage;

measuring an amplitude of the power voltage during at least part of the unload; and

adjusting the periodic signal based on the measured amplitude of the power voltage.

20. The device as recited in claim 19, wherein the periodic signal comprises a square wave.

21. The device as recited in claim 20, wherein the control circuitry is further configured to adjust the periodic signal by adjusting a duty cycle of the periodic signal.

22. The device as recited in claim 21, wherein the control circuitry is further configured to adjust the periodic signal by increasing the duty cycle of the periodic signal as the measured amplitude of the power voltage decreases.

23. The device as recited in claim 20, wherein the control circuitry is further configured to adjust the periodic signal by adjusting a period of the periodic signal.

24. The device as recited in claim 20, wherein the control circuitry is further configured to adjust the periodic signal by decreasing the period of the periodic signal as the measured amplitude of the power voltage decreases.

25. The device as recited in claim 19, wherein the control circuitry is further configured to first adjust the periodic signal when the measured amplitude of the power voltage falls below a first threshold.

26. The device as recited in claim 25, wherein the control circuitry is further configured to second adjust the periodic signal when the measured amplitude of the power voltage falls below a second threshold lower than the first threshold.

27. The device as recited in claim 25, wherein the control circuitry is further configured to:

generate a regulated voltage based on the power voltage; and

generate the first threshold based on the regulated voltage.