SENSOR ERROR DETECTION AND CORRECTION

• US 20180159455A1
• Filed: 12/02/2016
• Published: 06/07/2018
• Est. Priority Date: 12/02/2016
• Status: Active Grant

• Current Assignee: Arm Ltd. (United Kingdom) (SoftBank Group Corp.)
• Original Assignee: Arm Ltd. (United Kingdom) (SoftBank Group Corp.)
• Inventors: Pietromonaco, David Victor
• Granted Patent: US 10,236,815 B2
• Time in Patent Office: Days
• CPC Class Codes: H02K 11/21 Devices for sensing speed or position, or actuated thereby specially adapted for machines having non-mechanical commutating devices H02K29/06, H02K29/14
• CPC Class Codes: H02K 11/225 Detecting coils
• CPC Class Codes: H02K 29/12 using detecting coils using the machine windings as detecting coil
• CPC Class Codes: H02P 2203/00 Indexing scheme relating to controlling arrangements characterised by the means for detecting the position of the rotor
• CPC Class Codes: H02P 23/14 Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage
• CPC Class Codes: H02P 25/089 Sensorless control direct torque control H02P23/30
• CPC Class Codes: H02P 6/15 Controlling commutation time
• CPC Class Codes: H02P 6/153 wherein the commutation is advanced from position signals phase in function of the speed

Abstract

Electric motors may include one or more sensors usable to determine rotor alignment and/or speed. A method and apparatus for rotor alignment and/or speed error detection and/or correction are proposed, such as using signals from one or more sensors. A method and apparatus for controlling stator tooth activation based, at least in part, on corrections and offsets is also disclosed.

Claims

1. A method comprising:

determining an estimated speed and estimated alignment of a rotor based, at least in part, on signals obtained from at least one sensor of a plurality of sensors;

determining an alignment offset based, at least in part, on the estimated rotor speed and alignment of the rotor; and

transmitting one or more current pulses to one or more coil windings of a stator based, at least in part, on the alignment offset.

2. The method of claim 1, wherein determining the estimated rotor speed further comprises recording a first timestamp corresponding to a time at which a sensor of the plurality of sensors detects a rotor tooth and recording a second timestamp corresponding to a next time at which the sensor of the plurality of sensors detects a rotor tooth.

3. The method of claim 2, further comprising determining the estimated rotor speed based, at least in part, on a time difference between the first timestamp and the second timestamp.

4. The method of claim 1, wherein determining the estimated rotor alignment further comprises recording a timestamp corresponding to a time at which a sensor of the plurality of sensors detects a rotor tooth and two or more other sensors of the plurality of sensors do not detect a rotor tooth.

5. The method of claim 1, further comprising:

determining a timing window corresponding to a time at which a rotor tooth is expected to be detected by a sensor of the plurality of sensors; and

incrementing an error count responsive to a determination that the rotor tooth is not detected by the sensor of the plurality of sensors in the determined timing window.

6. The method of claim 5, further comprising abstaining from transmitting current pulses to the one or more coil windings of the stator responsive to a non-zero error count.

7. The method of claim 5, further comprising incrementing a good count responsive to detection of a rotor tooth in a subsequent timing window, and decreasing the error count responsive to a determination that the good count meets or exceeds a threshold.

8. The method of claim 1, wherein determining the alignment offset further comprises:

recording a first timestamp corresponding to a time at which a rotor tooth is detected by a sensor of the plurality of sensors;

recording a second timestamp corresponding to a time at which the rotor tooth is no longer detected by the sensor;

comparing the first and second timestamps with historical timestamps for the sensor to find a middle value for the sensor; and

determining the alignment offset based, at least in part, on the middle value and an expected rotor alignment, wherein the expected rotor alignment is based at least partly on the rotor speed.

9. The method of claim 1, further comprising determining a detection area offset based, at least in part, on the first and second timestamps.

10. An apparatus comprising:

a rotor and a stator;

an alignment sensing mechanism;

a driver; and

a controller to;

determine an estimated speed and estimated alignment of the rotor based, at least in part, on signals received from the alignment sensing mechanism;

determine an alignment offset based, at least in part, on the estimated rotor speed and alignment of the rotor; and

transmit one or more signals to the driver to enable transmission of current pulses to one or more coil windings of the stator based, at least in part, on the alignment offset.

11. The apparatus of claim 10, wherein the controller is further to record a first timestamp to correspond to a time at which a sensor of the alignment sensing mechanism detects a rotor tooth, and record a second timestamp to correspond to a next time at which the sensor of the alignment sensing mechanism detects a rotor tooth.

12. The apparatus of claim 11, wherein the controller is further to determine the estimated rotor speed to be based, at least in part, on a time difference between the first timestamp and the second timestamp.

13. The apparatus of claim 10, wherein the controller is further to record a timestamp to correspond to a time at which a sensor of the alignment sensing mechanism detects a rotor tooth and two or more other sensors of the alignment sensing mechanism do not detect a rotor tooth.

14. The apparatus of claim 10, wherein the controller is further to:

record a first timestamp to correspond to a time at which a rotor tooth is detected by a sensor of the alignment sensing mechanism;

record a second timestamp to correspond to a time at which the rotor tooth is no longer detected by the sensor;

compare the first and second timestamps with historical timestamps for the sensor to find a middle value for the sensor; and

determine the alignment offset to based, at least in part, on the middle value and an expected rotor alignment, wherein the expected rotor alignment is to be based at least partly on the rotor speed.

15. The apparatus of claim 10, wherein the controller is further to determine an area of detection offset to be based, at least in part, on the first and second timestamps.

16. An article comprising:

a non-transitory computer readable medium with instructions stored thereon that when executed by a processor of a controller are to;

determine an estimated speed and estimated alignment of a rotor based, at least in part, on signals obtained from an alignment sensing mechanism;

determine an alignment offset based, at least in part, on the estimated rotor speed and alignment of the rotor; and

transmit one or more current pulses to one or more coil windings of a stator based, at least in part, on the alignment offset.

17. The article of claim 16, further comprising instructions that when executed by the processor of the controller are to:

determine a timing window to correspond to a time at which a rotor tooth is expected to be detected by a sensor of the alignment sensing mechanism; and

increment an error count responsive to a determination that the rotor tooth is not detected by the sensor of the alignment sensing mechanism in the determined timing window.

18. The article of claim 17, further comprising instructions that when executed by the processor of the controller are to abstain from transmitting current pulses to the one or more coil windings of the stator responsive to a non-zero error count.

19. The article of claim 17, further comprising instructions that when executed by the processor of the controller are to increment a good count responsive to detection of a rotor tooth in a subsequent timing window, and decrease the error count responsive to a determination that the good count meets or exceeds a threshold.

20. A system comprising:

means for determining an estimated speed and estimated alignment of a rotor based, at least in part, on signals obtained from at least one of an alignment sensing mechanism;

means for determining an alignment offset based, at least in part, on the estimated rotor speed and alignment of the rotor; and

means for transmitting one or more current pulses to one or more coil windings of a stator based, at least in part, on the alignment offset.