Position detection and monitoring
An apparatus includes a controller that controls a motor including multiple motor windings. To determine motor position, the controller is operative to supply current through the multiple windings of the motor. The multiple windings are coupled to a rotor of the motor. While supplying the current to the motor windings, the controller monitors a magnitude of the current supplied through the windings of the motor. Based on measured inductance associated with the motor as determined from the monitored current through the windings, the controller determines a (rotational) position of the rotor.
1. An apparatus comprising:
a controller operative to:
supply current through multiple windings of a motor;
monitor a magnitude of the current supplied through the multiple windings of the motor; and
based on inductance determined from the monitored magnitude of current supplied through the multiple windings, determine a position of a rotor of the motor.
2. The apparatus as in claim 1 , wherein the current is test current; and
wherein the controller is operative to supply the test current through the multiple windings and determine the position of the rotor while the rotor of the motor is not rotating.
3. The apparatus as in claim 1 , wherein the current supplied through the multiple windings of the motor does not cause the rotor of the motor to rotate.
4. The apparatus as in claim 1 , wherein the controller is operative to supply the current, monitor the magnitude, and determine the position of the rotor while a speed of rotating the rotor is above zero and below a threshold value.
5. The apparatus as in claim 1 , wherein a frequency of the current supplied through the multiple windings is greater than a rotational frequency of the rotor.
6. The apparatus as in claim 1 , wherein the controller is operative to control supply of the current through the multiple windings of the motor based on space vector modulation.
7. The apparatus as in claim 1 , wherein the controller is further operative to:
via a transformation function, convert the monitored magnitude of the current through the multiple windings of the motor into an inductance function, a magnitude of the inductance function varying over time.
8. The apparatus as in claim 7 , wherein the controller is further operative to identify the position of the rotor based on a minimum identified inductance value.
9. The apparatus as in claim 7 , wherein the transformation function includes a Clarke transformation and a Cartesian to Polar coordinates transformation.
10. The apparatus as in claim 1 , wherein the controller is further operative to:
derive an inductance value that varies over time based on the magnitude of current supplied through the windings; and
determine the position of the rotor based on the magnitude of the inductance value in a given control cycle of supplying the current through the multiple windings.
11. The method as in claim 1 further comprising:
controlling sinusoidal supply of the current through multiple windings of the motor based on space vector modulation.
12. A system comprising:
a circuit substrate; and
the apparatus of claim 1 coupled to the circuit substrate.
13. A method comprising:
receiving a circuit substrate; and
coupling the apparatus of claim 1 to the circuit substrate.
14. The apparatus as in claim 1 , wherein the motor is a brushless DC motor.
15. The apparatus as in claim 1 , wherein the controller is further operative to:
measure the magnitude of the current supplied through the multiple windings of the motor; and
derive the inductance from the measured magnitude of the current.
16. The apparatus as in claim 1 , wherein the controller is further operative to:
derive an inductance value that varies over time based on the magnitude of current supplied through the multiple windings.
17. The apparatus as in claim 16 , wherein the controller is further operative to:
determine the position of the rotor based on the magnitude of the inductance value.
18. The apparatus as in claim 1 , wherein the controller is further operative to:
determine the position of the rotor within a period of a control cycle of supplying the current through the multiple windings of the motor.
19. The apparatus as in claim 1 , wherein a magnitude of the inductance varies depending on the position of the rotor.
20. The apparatus as in claim 19 , wherein the magnitude of the inductance corresponds to the position of the rotor.
21. The apparatus as in claim 1 , wherein the controller is further operative to:
calculate the inductance based on the magnitude of current;
identify a valley of the inductance; and
derive the position of the rotor via mapping of the valley to an angle value indicative of the position.
22. The apparatus as in claim 21 , wherein the controller is further operative to:
use the derived position of the rotor to select an appropriate phase of subsequent supply current to drive the multiple windings to achieve a desired torque associated with the rotor.
23. A method comprising:
supplying current through multiple windings of a motor;
monitoring a magnitude of the current supplied through the multiple windings of the motor; and
based on inductance determined from the monitored magnitude of current supplied through the multiple windings, derive a position of a rotor of the motor.
24. The method as in claim 23 further comprising:
supplying the current through the multiple windings; and
determining the position of the rotor while the rotor of the motor is not rotating.
25. The method as in claim 23 , wherein the current supplied through the multiple windings of the motor does not cause the rotor of the motor to rotate.
26. The method as in claim 23 further comprising:
supplying the current, monitoring the magnitude, and determining the position while a speed of rotating the rotor is greater than zero but below a threshold value.
27. The method as in claim 23 , wherein a frequency of the current supplied through the multiple windings is greater than a rotational frequency of the rotor.
28. The method as in claim 23 further comprising:
converting the monitored magnitude of the current through the multiple windings of the motor into an inductance signal, a magnitude of the inductance signal varying over time.
29. The method as in claim 28 further comprising:
identifying the position of the rotor based on a minimum inductance value of the inductance signal derived from the monitored magnitude of current through the windings.
30. The method as in claim 28 , wherein generation of the inductance signal includes application of a Clarke transformation function and a Cartesian to Polar coordinates transformation function.
31. The apparatus as in claim 23 further comprising:
deriving an inductance value that varies over time based on the magnitude of current supplied through the windings; and
determining the position of the rotor based on the magnitude of the inductance value in a given control cycle of supplying the current through the windings.
32. Computer-readable storage media having instructions stored thereon, the instructions, when executed by computer processor hardware, cause the computer processor hardware to:
supply test current through multiple windings of a motor;
monitor a magnitude of the test current supplied through the multiple windings of the motor; and
based on inductance determined from the monitored magnitude of test current supplied through the multiple windings, determine a position of a rotor of the motor.