Granted Patent B1

US 9,355,676 · App. 14/668,949 · Granted May 31, 2016

Abstract

Claims (207)

1. A data storage device comprising:

a disk;

a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings;

a head actuated over the disk; and

control circuitry powered by a supply voltage, the control circuitry configured to:

commutate the windings of the spindle motor based on a commutation sequence while applying a periodic driving voltage to each winding, wherein the periodic driving voltage comprises an operating amplitude during normal operation; and

when the supply voltage falls below a threshold, configure the spindle motor into a power generator by at least adjusting the amplitude and a phase of the periodic driving voltage so that a periodic current flowing through each winding is substantially opposite in phase from a sinusoidal back electromotive force (BEMF) voltage generated by each winding,

wherein adjusting the amplitude and the phase of the periodic driving voltage comprises adjusting at least one of the amplitude and the phase based on an amplitude of the sinusoidal BEMF voltage, a resistance of the windings, and an inductance of the windings.

2. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to:

measure a rotation speed of the spindle motor; and

adjust the amplitude of the periodic driving voltage based on the measured rotation speed.

3. The data storage device as recited in claim 2 , wherein the control circuitry is further configured to adjust the amplitude of the periodic driving voltage based on:

√{square root over ((| Vb ( RPM )|− R|I |) 2 +( Lω ecyc |I |) 2 )}

where:

RPM represents the measured rotation speed;

|Vb(RPM)| represents an amplitude of the sinusoidal BEMF voltage as a function of the measured rotation speed;

R represents the resistance;

L represents the inductance;

ω ecyc represents a frequency of the sinusoidal BEMF voltage; and

|I| represents an amplitude of the periodic current.

4. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to:

measure a rotation speed of the spindle motor; and

adjust the phase of the periodic driving voltage based on the measured rotation speed.

5. The data storage device as recited in claim 4 , wherein the control circuitry is further configured to adjust the phase of the periodic driving voltage based on:

tan

-

1

⁡

(



Vb

⁡

(

RPM

)



-

R

⁢



I



L

ω

⁢

⁢

ecyc

⁢



I



)

where:

RPM represents the measured rotation speed;

|Vb(RPM)| represents an amplitude of the sinusoidal BEMF voltage as a function of the measured rotation speed;

R represents the resistance;

L represents the inductance;

ω ecyc represents a frequency of the sinusoidal BEMF voltage; and

|I| represents an amplitude of the periodic current.

6. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to:

compare the supply voltage to a target voltage to generate an error signal; and

adjust the phase of the periodic driving voltage and the amplitude of the periodic driving voltage based on the error signal.

7. The data storage device as recited in claim 6 , wherein adjusting the phase of the periodic driving voltage and the amplitude of the periodic driving voltage based on the error signal adjusts an amplitude of the current flowing through each winding.

8. The data storage device as recited in claim 6 , wherein:

the control circuitry comprises a voltage regulator; and

the target voltage substantially maximizes an efficiency of the voltage regulator powered by the supply voltage.

9. A data storage device comprising:

a disk;

a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings;

a head actuated over the disk; and

control circuitry powered by a supply voltage, the control circuitry configured to:

commutate the windings of the spindle motor based on a commutation sequence while applying a periodic driving voltage to each winding, wherein the periodic driving voltage comprises an operating amplitude during normal operation; and

when the supply voltage falls below a threshold, configure the spindle motor into a power generator by at least:

comparing the supply voltage to a target voltage to generate an error signal; and

adjusting the amplitude and a phase of the periodic driving voltage based on the error signal.

10. The data storage device as recited in claim 9 , wherein the control circuitry is further configured to adjust the amplitude and phase of the periodic driving voltage so that a periodic current flowing through each winding is substantially opposite in phase from a sinusoidal back electromotive force (BEMF) voltage generated by each winding.

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

rotating a disk using a spindle motor comprising a plurality of windings;

actuating a head over the disk;

commutating the windings of the spindle motor based on a commutation sequence while applying a periodic driving voltage to each winding, wherein the periodic driving voltage comprises an operating amplitude during normal operation; and

when a supply voltage for powering the data storage device falls below a threshold, configuring the spindle motor into a power generator by at least adjusting the amplitude and a phase of the periodic driving voltage so that a periodic current flowing through each winding is substantially opposite in phase from a sinusoidal back electromotive force (BEMF) voltage generated by each winding,

wherein adjusting the amplitude and the phase of the periodic driving voltage comprises adjusting at least one of the amplitude and the phase based on an amplitude of the sinusoidal BEMF voltage, a resistance of the windings, and an inductance of the windings.

12. The method as recited in claim 11 , further comprising:

measuring a rotation speed of the spindle motor; and

adjusting the amplitude of the periodic driving voltage based on the measured rotation speed.

13. The method as recited in claim 12 , further comprising adjusting the amplitude of the periodic driving voltage based on:

√{square root over ((| Vb ( RPM )|− R|I |) 2 +( Lω ecyc |I |) 2 )}

where:

RPM represents the measured rotation speed;

|Vb(RPM)| represents an amplitude of the sinusoidal BEMF voltage as a function of the measured rotation speed;

R represents the resistance;

L represents the inductance;

ω ecyc represents a frequency of the sinusoidal BEMF voltage; and

|I| represents an amplitude of the periodic current.

14. The method as recited in claim 11 , further comprising:

measuring a rotation speed of the spindle motor; and

adjusting the phase of the periodic driving voltage based on the measured rotation speed.

15. The method as recited in claim 14 , further comprising adjusting the phase of the periodic driving voltage based on:

tan

-

1

⁡

(



Vb

⁡

(

RPM

)



-

R

⁢



I



L

ω

⁢

⁢

ecyc

⁢



I



)

where:

RPM represents the measured rotation speed;

|Vb(RPM)| represents an amplitude of the sinusoidal BEMF voltage as a function of the measured rotation speed;

R represents the resistance;

L represents the inductance;

ω ecyc represents a frequency of the sinusoidal BEMF voltage; and

|I| represents an amplitude of the periodic current.

16. The method as recited in claim 11 , further comprising:

comparing the supply voltage to a target voltage to generate an error signal; and

adjusting the phase of the periodic driving voltage and the amplitude of the periodic driving voltage based on the error signal.

17. The method as recited in claim 16 , wherein adjusting the phase of the periodic driving voltage and the amplitude of the periodic driving voltage based on the error signal adjusts an amplitude of the current flowing through each winding.

18. The method as recited in claim 16 , wherein the target voltage substantially maximizes an efficiency of a voltage regulator powered by the supply voltage.

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

rotating a disk using a spindle motor comprising a plurality of windings;

actuating a head over the disk;

commutating the windings of the spindle motor based on a commutation sequence while applying a periodic driving voltage to each winding, wherein the periodic driving voltage comprises an operating amplitude during normal operation; and

when a supply voltage for powering the data storage device falls below a threshold, configuring the spindle motor into a power generator by at least:

comparing the supply voltage to a target voltage to generate an error signal; and

adjusting the amplitude and a phase of the periodic driving voltage based on the error signal.

20. The method as recited in claim 19 , further comprising adjusting the amplitude and phase of the periodic driving voltage so that a periodic current flowing through each winding is substantially opposite in phase from a sinusoidal back electromotive force (BEMF) voltage generated by each winding.

21. Control circuitry powered by a supply voltage, the control circuitry configured to:

commutate windings of a spindle motor based on a commutation sequence while applying a periodic driving voltage to each winding, wherein the periodic driving voltage comprises an operating amplitude during normal operation; and

when the supply voltage falls below a threshold, configure the spindle motor into a power generator by at least adjusting the amplitude and a phase of the periodic driving voltage so that a periodic current flowing through each winding is substantially opposite in phase from a sinusoidal back electromotive force (BEMF) voltage generated by each winding,

wherein adjusting the amplitude and the phase of the periodic driving voltage comprises adjusting at least one of the amplitude and the phase based on an amplitude of the sinusoidal BEMF voltage, a resistance of the windings, and an inductance of the windings.

22. The control circuitry as recited in claim 21 , further configured to:

measure a rotation speed of the spindle motor; and

adjust the amplitude of the periodic driving voltage based on the measured rotation speed.

23. The control circuitry as recited in claim 22 , further configured to adjust the amplitude of the periodic driving voltage based on:

√{square root over ((| Vb ( RPM )|− R|I |) 2 +( Lω ecyc |I |) 2 )}

where:

RPM represents the measured rotation speed;

|Vb(RPM)| represents an amplitude of the sinusoidal BEMF voltage as a function of the measured rotation speed;

R represents the resistance;

L represents the inductance;

ω ecyc represents a frequency of the sinusoidal BEMF voltage; and

|I| represents an amplitude of the periodic current.

24. The control circuitry as recited in claim 21 , further configured to:

measure a rotation speed of the spindle motor; and

adjust the phase of the periodic driving voltage based on the measured rotation speed.

25. The control circuitry as recited in claim 24 , further configured to adjust the phase of the periodic driving voltage based on:

tan

-

1

⁡

(



Vb

⁡

(

RPM

)



-

R

⁢



I



L

ω

⁢

⁢

ecyc

⁢



I



)

where:

RPM represents the measured rotation speed;

|Vb(RPM)| represents an amplitude of the sinusoidal BEMF voltage as a function of the measured rotation speed;

R represents the resistance;

L represents the inductance;

ω ecyc represents a frequency of the sinusoidal BEMF voltage; and

|I| represents an amplitude of the periodic current.

26. Control circuitry powered by a supply voltage, the control circuitry configured to:

commutate windings of a spindle motor based on a commutation sequence while applying a periodic driving voltage to each winding, wherein the periodic driving voltage comprises an operating amplitude during normal operation; and

when the supply voltage falls below a threshold, configure the spindle motor into a power generator by at least:

comparing the supply voltage to a target voltage to generate an error signal; and

adjusting the amplitude and a phase of the periodic driving voltage based on the error signal.

27. The control circuitry as recited in claim 26 , further configured to adjust the amplitude and phase of the periodic driving voltage so that a periodic current flowing through each winding is substantially opposite in phase from a sinusoidal back electromotive force (BEMF) voltage generated by each winding.

Assignments (7)