Orientation of a rotor

1. An apparatus comprising:

sample-accumulation logic to generate, over a time duration, a value indicative of inductance at least partially responsive to a probe signal provided to a stator of a motor;

a probe-current discriminator to generate a further value indicative of an orientation of a rotor of the motor at least partially responsive to the generated value; and

update logic to update, at a commutation angle estimator or a phase-locked loop, an estimated electrical angle of a rotor at least partially responsive to a state of the further value indicating the orientation of the rotor to be off by 180°.

2. The apparatus of claim 1 , comprising a probe-signal generator to generate the probe signal and a transform to provide the probe signal along a d-axis of the motor.

3. The apparatus of claim 1 , comprising a probe-signal generator to generate the probe signal, the probe signal comprising a first current during a first-current duration and a second current during a second-current duration.

4. The apparatus of claim 3 , wherein the first current and the second current are nonzero and have opposite signs.

5. The apparatus of claim 3 , wherein the probe-current discriminator is to generate the further value by comparing a first value indicative of inductance during the first-current duration to a second value indicative of inductance during the second-current duration.

6. The apparatus of claim 3 , wherein the probe signal comprises the first current during two or more first-current durations and the second current during one or more second-current durations.

7. The apparatus of claim 6 , wherein the two or more first-current durations are interleaved with the one or more second-current durations.

8. The apparatus of claim 1 , wherein the update logic is to adjust, at the commutation angle estimator or the phase-locked loop, the estimated electrical angle by 180° at least partially responsive to the state of the further value indicating the orientation of the rotor to be off by 180°.

9. A method comprising:

providing an excitation signal to a stator of a motor to induce a response signal;

providing a probe signal to the stator;

generating a signal indicative of inductance at least partially responsive to the induced response signal;

observing, over a time duration, the generated signal at least partially responsive to the provided probe signal;

generating a further signal indicative of an orientation of a rotor of the motor at least partially responsive to the observed signal; and

updating, at a commutation angle estimator or a phase-locked loop, an estimated electrical angle of a rotor at least partially responsive to a state of the further signal indicating the orientation of the rotor to be off by 180°.

10. The method of claim 9 , comprising providing the probe signal along a d-axis of the motor.

11. The method of claim 9 , comprising generating the probe signal comprising a first current during a first-current duration and a second current during a second-current duration.

12. The method of claim 11 , wherein the first current and the second current are nonzero and have opposite signs.

13. The method of claim 11 , wherein generating the further signal comprises comparing a first portion of the observed signal indicative of inductance during the first-current duration to a second portion of the observed signal indicative of inductance during the second-current duration.

14. The method of claim 9 , wherein providing the probe signal to the stator comprises providing a first current during two or more first-current durations and providing a second current during one or more second-current durations.

15. The method of claim 14 , interleaving the two or more first-current durations with the one or more second-current durations.

16. The method of claim 9 , wherein updating the estimated electrical angle comprises adjusting, at the commutation angle estimator or the phase-locked loop, the estimated electrical angle by 180°.

17. The method of claim 9 , wherein updating the process variable comprises updating a state of a current-loop integrator responsive to the orientation of the rotor.

18. An apparatus comprising:

one or more circuits to:

provide, responsive to a controller, an oscillating signal to a stator of a motor to induce a response signal;

generate a signal indicative of inductance at least partially responsive to the induced response signal;

observe, over a time duration, the generated signal at least partially responsive to providing a probe signal to the stator;

generate a further signal indicative of an orientation of a rotor of the motor at least partially responsive to the observed signal; and

update, at a commutation angle estimator or a phase-locked loop, an estimated electrical angle of a rotor at least partially responsive to the further signal indicating the orientation of the rotor to be off by 180°,

wherein the update to the estimated electrical angle adjusts the estimated electrical angle of the rotor by 180°.

19. The apparatus of claim 18 , wherein the one or more circuits generate the probe signal comprising a first current during a first-current duration and a second current during a second-current duration.

20. The apparatus of claim 19 , wherein the one or more circuits compare a first signal of the observed signal indicative of inductance during the first-current duration to a second signal of the observed signal indicative of inductance during the second-current duration.

21. The apparatus of claim 18 , wherein the one or more circuits apply the probe signal to the stator comprising providing a first current during one or more first-current durations and providing a second current during one or more second-current durations.