Controlling a motor with two or more Hall sensors

Patent metadata

Field	Value
Publication number	US-9239345-B2
Application number	US-201314085164-A
Country	US
Kind code	B2
Filing date	Nov 20, 2013
Priority date	Nov 20, 2013
Publication date	Jan 19, 2016
Grant date	Jan 19, 2016

Abstract

A motor system includes a motor including two Hall sensors configured to output binary values, and a controller configured to control the motor. The two Hall sensors are placed 120 or 60 electrical degrees apart. The controller is operable to monitor output signals of the two Hall sensors and to determine a third Hall sensor output binary value. The controller is operable to fulfill the commanded requirements to operate in a servo system, by controlling commutation of a drive current into the motor, and by keeping track of the motor rotor position based on the third generated signal and the outputs of the two Hall sensors.

First claim

The invention claimed is:

1. A motor system comprising:
a motor comprising two Hall sensors configured to output binary values, the two Hall sensors being placed 120 electrical degrees apart; and
a controller configured to control the motor, the controller being operable to:
monitor output signals of the two Hall sensors;
when the output signals of the two Hall sensors are different binary values, determine a third signal to be alternating between the binary values at a frequency no less than a maximum state transition frequency of the motor;
control commutation of a drive current into the motor based on the third signal and the outputs of the two Hall sensors; and
update a motor position counter based on a logic state combination of the output signals of the two Hall sensors by steps comprising:
monitoring a first logic state combination transitioning to a second logic state combination;
monitoring the second logic state combination transitioning to a third logic state combination;
when the third logic state combination comprises two same binary values;
comparing the third logic state combination with the first logic state combination;
if the third logic state combination is the same as the first logic state combination, updating the motor position counter by one count; and
if the third logic state combination is not the same as the first logic state combination, updating the motor position counter by two counts.

2. The motor system of claim 1 , wherein determining the third signal comprises generating the third signal.

3. The motor system of claim 1 , wherein the controller is configured such that, when the output signals of the two Hall sensors have a same binary value, the controller is operable to determine the third signal to be a binary value other than the same binary value.

4. The motor system of claim 3 , wherein the controller is operable to control the commutation of the drive current into the motor based on the third signal and the outputs of the two Hall sensors according to a commutation truth table for a motor with Hall sensors separated by 120 electrical degrees.

5. The motor system of claim 1 , wherein the controller is configured such that, when the output signals of the two Hall sensors have a same binary value, the controller is operable to determine the third signal to be the same binary value.

6. The motor system of claim 5 , wherein the controller is operable to control the commutation of the drive current into the motor based on the third signal and the outputs of the two Hall sensors according to a commutation truth table of a motor with Hall sensors separated by 60 electrical degrees.

7. The motor system of claim 1 , wherein the controller is operable to update the motor position counter based on the logic state combination of the output signals of the two Hall sensors by the steps comprising:
when the third logic state combination comprises two different binary values, updating the motor position counter by one count.

8. The motor system of claim 1 , wherein the controller is operable to update the motor position counter based on the logic state combination of the output signals of the two Hall sensors by the steps comprising decoding a moving direction of the motor based on the third logic state combination and the second logic state combination.

9. The motor system of claim 1 , wherein the motor comprises a third Hall sensor configured to output binary values and the controller is operable to monitor an output signal of the third Hall sensor.

10. The motor system of claim 9 , wherein the controller is further operable to force the motor to move by sequentially flipping one of the output signals of the two Hall sensors and the third Hall sensor from one binary value to another binary value.

11. The motor system of claim 9 , wherein the controller is operable to determine the third signal by using the third signal as a compensated output signal of the third Hall sensor.

12. The motor system of claim 9 , wherein the controller is further operable to identify the third Hall sensor as a failed Hall sensor based on a logic state combination of the output signals of the two Hall sensors and the output signal of the third Hall sensor.

13. The motor system of claim 12 , wherein the controller is operable to identify the third Hall sensor as the failed Hall sensor by steps comprising:
detecting a first fault logic state combination of the output signals of the two Hall sensors and the output signal of the third Hall sensor;
detecting a second fault logic state combination of the output signals of the two Hall sensors and the output signal of the third Hall sensor; and
identifying that the output signal of the third Hall sensor remains unchanged during a period from the first fault logic state combination to the second fault logic state combination.

14. The motor system of claim 13 , wherein the second fault logic state combination is at least 360 electrical degrees from the first fault logic state combination.

15. The motor system of claim 13 , wherein the third Hall sensor is 120 electrical degrees apart from either of the two Hall sensors, and the first fault logic state combination comprises a combination of three same binary values, and the second fault logic state combination is the same as the first fault logic state combination.

16. The motor system of claim 13 , wherein the third Hall sensor is 60 electrical degrees apart from each of the two Hall sensors, and the first fault logic state combination comprises a combination where the output signals of the two Hall sensors have a same binary value and the output signal of the third Hall sensor has a binary value other than the same binary value, and the second fault logic state combination is the same as the first fault logic state combination.

17. A motor system comprising:
a motor comprising two Hall sensors configured to output binary values, the two Hall sensors being placed 60 electrical degrees apart; and
a controller configured to control the motor, the controller being operable to:
monitor output signals of the two Hall sensors;
when the output signals of the two Hall sensors are different binary values, determine a third signal to be a same binary value as an output signal of a pivot Hall sensor, wherein the pivot Hall sensor is one of the two Hall sensors;
control commutation of a drive current into the motor based on the third signal and the output signals of the two Hall sensors; and
update a motor position counter based on a logic state combination of the output signals of the two Hall sensors by steps comprising:
monitoring a first logic state combination transitioning to a second logic state combination;
monitoring the second logic state combination transitioning to a third logic state combination;
when the third logic state combination comprises two different binary values,
comparing the third logic state combination with the first logic state combination;
if the third logic state combination is the same as the first logic state combination, updating the motor position counter by one count; and
if the third logic state combination is not the same as the first logic state combination, updating the motor position counter by two counts.

18. The motor system of claim 16 , wherein determining the third signal comprises generating the third signal.

19. The motor system of claim 16 , wherein the controller is configured such that, when the output signals of the two Hall sensors are two same binary values, the controll

Assignees

• Woodward Inc

Inventors

• Liu Raymond
• Chung Estella

Classifications

• G01R23/00 Primary

  Arrangements for measuring frequencies; Arrangements for analysing frequency spectra · CPC title

• H02P29/032

  Preventing damage to the motor, e.g. setting individual current limits for different drive conditions · CPC title

• H02P6/34

  Modelling or simulation for control purposes · CPC title

• G01R33/07 Primary

  Hall effect devices · CPC title

• H02P6/12

  Monitoring commutation; Providing indication of commutation failure · CPC title