SYSTEM AND METHOD FOR DETERMINING ANGULAR POSITION AND CONTROLLING ROTOR ORIENTATION

• US 20070176568A1
• Filed: 01/17/2007
• Published: 08/02/2007
• Est. Priority Date: 01/17/2006
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: De Lair, Charles, Bugge, John, Robichaux, Jerry, Lafontaine, Eric
• Granted Patent: US 7,579,799 B2
• Time in Patent Office: Days
• US Class Current: 318/400.60
• CPC Class Codes: G01R 33/0029 Treating the measured signals, e.g. removing offset or noise
• CPC Class Codes: H02P 6/15 Controlling commutation time
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position

Abstract

Methods and devices for determining the position and/or angular orientation of a rotating shaft. Exemplary features include a sensor module and a position determination module. Sensor module may include a plurality of Hall Effect devices (HEDs) arranged at a specified angular separation to produce a signal in response to rotation of the shaft. Position module may be responsive to sensor module to produce a converted signal, determine an error term, and produce a position estimate. Converted signal may be produced by processing the HED signals into sinusoidal reference signals having offset scale and amplitude scale factors. Error term may be determined by processing the converted signals to produce an estimated position signal. Position estimate may be produced by processing the error term. Refined position measurement may be achieved by iterative elimination of regressive differences between position estimates with minimization of absolute magnitude of error term.

Claims

1. A system for measuring the angular orientation of a rotor, said system comprising:

a rotor assembly comprising a plurality of annularly disposed motor field pole magnetic domains;

a sensor module having at least two HEDs disposed at a specified relative angular separation with respect to each other, wherein the sensor module is suitably configured to produce a plurality of input signals in response to magnetic flux variation corresponding to axial rotation of the motor field pole magnetic domains; and

a position measurement module suitably configured to;

process said input signals to produce converted sinusoidal reference signals, wherein said sinusoidal reference signals have at least one of an offset scale factor and an amplitude scale factor;

determine an error term by processing said converted reference signals to produce a position estimate signal corresponding to an approximate measurement of angular orientation of the rotor; and

subsequently produce a refined measurement of angular orientation of the rotor by processing the error term.

2. The system of claim 1, wherein the production of a refined measurement of angular orientation comprises iterative elimination of regressive differences between a plurality of angular orientation estimates.

3. The system of claim 1, wherein the rotor is suitably configured to rotate in response to actuation of at least two motor field pole magnetic domains.

4. The system of claim 3, wherein the normal vector corresponding to the transverse surface of the magnetic domains is substantially coincident with the rotational axis of the rotor.

5. The system of claim 3, wherein at least two HEDs are arranged annularly with respect to the principal axis such that the HED signals produced are sinusoidal and out of phase by 90 degrees with respect to one another.

6. The system of claim 1, wherein:

the converted sinusoidal signals HED1_Sin, HED2_Cos) are produced in accordance with;

HED1_Sin=(HED1_—

V−

B1)*X1 and
HED2_Cos=(HED2_—

V−

B2)*X2;

the error term (sin_error) is produced in accordance with;

sin_error=HED1_Sin*cos(pos_—

est(i−

1)*n/2)−

HED2_Cos*sin(pos_—

est(i−

1)*n/2);

and

the position estimate (pos_est(i)) is produced in accordance with;

$\mathrm{pos\_est}<br><br>\left(i\right)=\mathrm{sin\_error}<br><br>\left(i\right)*\left[\frac{K_1+K_1<br><br>K_2<br><br>s}{s^2}\right].$

7. The system of claim 6, wherein the position measurement module determines at least one of angular acceleration and angular velocity of the rotor by processing the position estimate (pos_est(i)).

8. The system of claim 6, wherein the value of at least one of X1, X2, B1, and B2 is adaptively identified.

9. The system of claim 1, further comprising a control module responsive to the position measurement module, wherein the control module is suitably configured to actuate at least two motor field pole magnetic domains for angular positioning of the rotor.

10. A method for measuring the angular orientation of a rotor, said method comprising the steps of:

providing a rotor assembly comprising a plurality of annularly disposed motor field pole magnetic domains;

providing a sensor module having at least two HEDs disposed at a specified relative angular separation with respect to each other, wherein the sensor module is suitably configured to produce a plurality of input signals in response to magnetic flux variation corresponding to axial rotation of the motor field pole magnetic domains; and

providing a position measurement module suitably configured for;

processing said input signals to produce converted sinusoidal reference signals, wherein said sinusoidal reference signals have at least one of an offset scale factor and an amplitude scale factor;

determining an error term by processing said converted reference signals to produce a position estimate signal corresponding to an approximate measurement of angular orientation of the rotor; and

subsequently producing a refined measurement of angular orientation of the rotor by processing the error term.

11. The method of claim 10, wherein the production of a refined measurement of angular orientation comprises iterative elimination of regressive differences between a plurality of angular orientation estimates.

12. The method of claim 10, wherein the rotor is suitably configured to rotate in response to actuation of at least two motor field pole magnetic domains.

13. The method of claim 10, wherein the normal vector corresponding to the transverse surface of the magnetic domains is substantially coincident with the rotational axis of the rotor.

14. The method of claim 10, wherein at least two HEDs are arranged annularly with respect to the principal axis of the rotor at such that the HED signals produced are sinusoidal and out of phase by 90 degrees with respect to one another.

15. The method of claim 10, wherein:

the converted sinusoidal signals (HED1_Sin, HED2_Cos) are produced in accordance with;

HED1_Sin=(HED1_—

V−

B1)*X1 and
HED2_Cos=(HED2_—

V−

B2)*X2;

the error term (sin_error) is produced in accordance with;

sin_error=HED1_Sin*cos(pos_—

est(i−

1)*n/2)−

HED2_Cos*sin(pos_—

est(i−

1)*n/2);

and

the position estimate (pos_est(i)) is produced in accordance with;

$\mathrm{pos\_est}<br><br>\left(i\right)=\mathrm{sin\_error}<br><br>\left(i\right)*\left[\frac{K_1+K_1<br><br>K_2<br><br>s}{s^2}\right].$

16. The method of claim 15, wherein the position measurement module determines at least one of angular acceleration and angular velocity of the rotor by processing the position estimate (pos_est(i)).

17. The method of claim 15, wherein the value of at least one of X1, X2, B1, and B2 is adaptively identified.

18. The method of claim 10, further comprising the step of providing a control module responsive to the position measurement module, wherein the control module is suitably configured to actuate at least two motor field pole magnetic domains for angular positioning of the rotor.

19. A method for controlling an electric motor, said method comprising the steps of:

providing a rotor assembly comprising a plurality of annularly disposed motor field pole magnetic domains;

providing a sensor module having at least two HEDs disposed at a specified relative angular separation with respect to each other, wherein the sensor module is suitably configured to produce a plurality of input signals in response to magnetic flux variation corresponding to axial rotation of the motor field pole magnetic domains;

providing a position measurement module suitably con figured for;

processing said input signals to produce converted sinusoidal reference signals, wherein said sinusoidal reference signals have at least one of an offset scale factor and an amplitude scale factor;

determining an error term by processing said converted reference signals to produce a position estimate signal corresponding to an approximate measurement of angular orientation of the rotor; and

subsequently producing a refined measurement of angular orientation of the rotor by processing the error term; and

providing a control module responsive to the position measurement module, wherein the control module is suitably configured to actuate at least two motor field pole magnetic domains for angular positioning of the rotor.

20. The method of claim 19, wherein the production of a refined measurement of angular orientation comprises iterative elimination of regressive differences between a plurality of angular orientation estimates.

21. The method of claim 19, wherein at least two HEDs are arranged annularly with respect to the principal axis of the rotor at such that the HED signals produced are sinusoidal and out of phase by 90 degrees with respect to one another.

22. The method of claim 19, wherein:

the converted sinusoidal signals (HED1_Sin, HED2_Cos) are produced in accordance with;

HED1_Sin=(HED1_—

V−

B1)*X1 and
HED2_Cos=(HED2_—

V−

B2)*X2;

the error term (sin_error) is produced in accordance with;

sin_error=HED1_Sin*cos(pos_—

est(i−

1)*n/2)−

HED2_Cos*sin(pos_—

est(i−

1)*n/2);

and

the position estimate (pos_est(k)) is produced in accordance with;

$\mathrm{pos\_est}<br><br>\left(i\right)=\mathrm{sin\_error}<br><br>\left(i\right)*\left[\frac{K_1+K_1<br><br>K_2<br><br>s}{s^2}\right].$

23. The method of claim 22, wherein the value of at least one of X1, X2, B1, and B2 is adaptively identified.