Claims
- 1. A method of operating a motor, comprising:
providing a motor driver circuit that applies current to rotate the motor over an output range of velocities from a lower threshold velocity to an upper operational velocity in response to a corresponding input range of commanded velocity values, wherein the motor driver circuit further rotates the motor at the threshold velocity in response to commanded velocity values corresponding to velocities less than the threshold velocity; and switching between application of current corresponding to a velocity within the output range of velocities and application of substantially no current to the spindle motor to maintain rotation of the motor at a selected velocity less than the threshold velocity.
- 2. The method of claim 1, wherein the switching step comprises switching between the application of current corresponding to the threshold velocity and the application of substantially no current to the motor.
- 3. The method of claim 1, further comprising a step of accelerating the motor from rest to a first velocity within the output range of velocities prior to the switching step.
- 4. The method of claim 1, wherein the providing step comprises providing the motor driver circuit as a proportional integral controller.
- 5. The method of claim 1, wherein the switching step is performed by a sliding mode controller.
- 6. The method of claim 1, wherein the switching step comprises measuring actual velocity of the motor, determining a velocity error in relation to the measured actual velocity and the selected velocity, and switching between the application of the current corresponding to the output velocity range and application of substantially no current in relation to the velocity error.
- 7. The method of claim 1, wherein the motor adaptively supports a rotatable data storage disc in a data storage device.
- 8. The method of claim 7, wherein the data storage device further comprises a data head that flies over the rotatable data storage disc, and wherein the method further comprises evaluating fly height characteristics of the head while the motor is maintained at the selected velocity.
- 9. A data storage device, comprising:
a motor configured to rotate at least one recording disc; a read/write head configured to write data to the disc and read data from the disc as the motor is rotated at an operational velocity; and a control circuit that applies current to rotate the motor over an output range of velocities from a lower threshold velocity to the upper operational velocity in response to a corresponding input range of commanded velocity values, wherein the control circuit further rotates the motor at the threshold velocity in response to commanded velocity values corresponding to velocities less than the threshold velocity; and a sliding mode control circuit that switches between application of current corresponding to a velocity within the output range of velocities and application of substantially no current to the motor to maintain rotation of the motor at a selected velocity less than the threshold velocity.
- 10. The apparatus of claim 9, wherein the sliding mode control circuit switches between the application of current corresponding to the threshold velocity and the application of substantially no current to the motor.
- 11. The apparatus of claim 9, wherein the control circuit further accelerates the motor from rest to a first velocity within the output range of velocities prior to the switching by the sliding mode control circuit.
- 12. The apparatus of claim 9, wherein the control circuit applies current using a proportional integral controller.
- 13. The apparatus of claim 9, wherein the sliding mode control circuit measures actual velocity of the motor, determines a velocity error in relation to the measured actual velocity and the selected velocity, and switches between the application of the current corresponding to the output velocity range and application of substantially no current in relation to the velocity error.
- 14. The apparatus of claim 13, wherein the velocity is measured by back electromotive force (bemf) detection circuitry.
- 15. The apparatus of claim 9, wherein the threshold velocity is determined for each configuration of data storage device.
- 16. The apparatus of claim 9, further comprising, circuitry for evaluating fly height characteristics of the head while the motor is maintained at the selected velocity.
- 17. A data storage device, comprising:
a motor configured to rotate at least one recording disc; a read/write head configured to write data to the disc and read data from the disc as the motor is rotated at an operational velocity; back electromagnetic force (bemf) detection circuitry coupled to the motor and which detects bemf from rotation of the motor; commutation circuitry coupled to the bemf detection circuitry and motor which electrically commutates the motor in relation to the detected bemf over a range of electrical rotational positions of the motor; and first means for controlling the velocity of the motor from a threshold velocity to the operational velocity; and second means for controlling the velocity of the motor below the threshold velocity.
- 18. The disc drive of claim 17, wherein the threshold velocity is substantially the minimum velocity by which the first means can control the motor.
- 19. The disc drive of claim 17, wherein the threshold velocity is limited by control electronics.
- 20. The disc drive of claim 17, wherein the second means is sliding mode control.
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Application No. 60/368,315 filed Mar. 28, 2002.
Provisional Applications (1)
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Number |
Date |
Country |
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60368315 |
Mar 2002 |
US |