Methods and apparatus to reduce the stopping time of spindle motors

1. A motor control system associated with a spindle motor, comprising:

a power source operatively coupled to one or more windings of the spindle motor to drive a rotation of the spindle motor;

a detector having one or more sensors to detect a status of the spindle motor by measuring a motor inductance, wherein the status includes a level of dissipation current flowing through the spindle motor; and

a controller coupled to the power source,

wherein the controller causes the power source to apply a voltage to the spindle motor for a duration in response to the level of dissipation current dropping below a threshold, and wherein the voltage increases the dissipation current and actively stops the spindle motor, the voltage having a first polarity different than a second polarity of a back electromotive force of the spindle motor.

2. A motor control system as defined in claim 1 , wherein the detector receives current signals from the one or more windings of the motor.

3. A method as defined in claim 1 , wherein the detector includes one or more sense resistors to provide information to the controller regarding the status of the motor.

4. A method as defined in claim 1 , wherein the controller further causes a plurality of switches to restrict the voltage from being applied to the motor.

5. A method as defined in claim 4 , further comprising a driver to control an operation of the plurality of switches.

6. A method as defined in claim 1 , wherein the voltage has a polarity similar to a back electromagnetic force generated by the rotation of the motor.

7. A method as defined in claim 1 , wherein the dissipation current is dissipated over a resistance of the motor.

8. A method as defined in claim 1 , wherein an average level of the dissipation current is controlled by adjusting an amplitude of the voltage.

9. A method as defined in claim 1 , wherein an average level of the dissipation current is controlled by adjusting the duration.

10. A method for actively breaking a spindle motor, the method comprising the steps of:

coupling a power source to one of more windings of the spindle motor for driving rotation of the spindle motor;

detecting a status of the spindle motor by measuring a motor inductance, wherein the status includes a level of dissipation current flowing through the spindle motor;

coupling a controller to the power source; and

causing the power source to apply a voltage to the spindle motor for a duration in response to the level of dissipation current dropping below a threshold, and wherein the voltage increases the dissipation current and actively stops the spindle motor, the voltage having a first polarity different than a second polarity of a back electromotive force of the spindle motor.

11. A method as defined in claim 10 , wherein the voltage has a polarity similar to a back electromagnetic force generated by a forward rotation of the motor.

12. A method as defined in claim 10 , further comprising removing the voltage from the motor when the motor comes to a stop.

13. A method as defined in claim 10 , further comprising removing the voltage from the motor when the motor reaches a predetermined rotational velocity.

14. A method as defined in claim 10 , wherein the predetermined rotational velocity is set to include a tolerance factor to avoid a reverse rotation of the motor.

15. A method as defined in claim 10 , further comprising adjusting the duration according to a progression of the motor to a next commutation state.

16. A method as defined in claim 10 , further comprising detecting whether the motor is in a commutation state for a time period exceeding a threshold.

17. A method as defined in claim 16 , further comprising removing the voltage from the motor in response to detecting the motor being in the commutation state beyond the threshold.

18. A method as defined in claim 10 , further comprising shorting each phase of the motor to ground after the duration.