ENHANCED INDUCTIVE SENSE USING MUTUAL INDUCTANCE

• US 20150295526A1
• Filed: 04/09/2014
• Published: 10/15/2015
• Est. Priority Date: 04/09/2014
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Inventors: Chew, Wei Seng, Xiong, Wei
• Granted Patent: US 9,379,650 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02P 21/18 Estimation of position or speed
• CPC Class Codes: H02P 6/182 using back-emf in windings
• CPC Class Codes: H02P 6/185 using inductance sensing, e.g. pulse excitation
• CPC Class Codes: H02P 6/186 using difference of inductance or reluctance between the phases
• CPC Class Codes: H02P 6/22 in a selected direction of rotation

Abstract

Methods and apparatus for determining rotor position in a motor including a rotor and stator windings. The method includes measuring inductive sense values for each pair of the stator windings by performing an inductive sense routine on the motor, measuring stator winding voltage values, induced by mutual inductance between windings, for each of the stator windings by performing a mutual inductance sensing routine on the motor, and determining the rotor position based on the inductive sense values and the stator winding voltage values.

Claims

1. A method for determining rotor position in a motor including a rotor and stator windings, comprising:

measuring inductive sense values for each pair of the stator windings by performing an inductive sense routine on the motor;

measuring stator winding voltage values, induced by mutual inductance between windings, for each of the stator windings by performing a mutual inductance sensing routine on the motor; and

determining the rotor position based on the inductive sense values and the stator winding voltage values.

2. A method for determining rotor position as defined in claim 1, wherein measuring inductive sense values comprises determining a time for a current through each pair of the stator windings to reach a current limit.

3. A method for determining rotor position as defined in claim 1, wherein measuring stator winding voltage values comprises determining if a winding voltage is positive or negative when a current is supplied through two other stator windings.

4. A method for determining rotor position as defined in claim 1, wherein determining the rotor position comprises accessing an entry in a table based on the inductive sense values and the stator winding voltage values.

5. A method for determining rotor position as defined in claim 1, wherein the motor includes three stator windings and wherein measuring inductive sense values includes measuring six inductive sense values.

6. A method for determining rotor position as defined in claim 1, wherein the motor includes three stator windings and wherein measuring stator winding voltage values comprises measuring six stator winding voltage values.

7. A method for determining rotor position as defined in claim 1, wherein measuring stator winding voltage values comprises supplying a current through a pair of the stator windings and measuring a voltage across a third winding of the stator windings.

8. A method for determining a rotor position as defined in claim 7, wherein measuring the voltage across the third winding comprises determining zero crossings of the voltage across the third winding.

9. A method for determining a rotor position as defined in claim 2, wherein determining the time to reach a current limit comprises sensing a voltage across a single sense resistor associated with the stator windings.

10. A method for determining a rotor position as defined in claim 2, wherein determining the time to reach a current limit comprises sensing a voltage across sense resistors associated with respective stator windings.

11. A method for determining rotor position in a motor including a rotor and three stator windings, comprising:

measuring inductive sense values for each pair of the stator windings by determining a time for a current through each pair of stator windings to reach a current limit;

measuring stator winding voltage values, induced by mutual inductance between windings, for each of the stator windings by supplying a current through a pair of the stator windings and measuring the zero crossings of a voltage across a third winding of the stator windings; and

determining the rotor position by accessing an entry in a table based on the measured inductive sense values and the measured stator winding voltage values.

12. Apparatus for determining rotor position in a motor including a rotor and stator windings, comprising:

first circuitry configured to measure inductive sense values for each pair of the stator windings by performing an inductive sense routine on the motor;

second circuitry configured to measure stator winding voltage values, induced by mutual inductance between windings, for each of the stator windings by performing a mutual inductance sensing routine on the motor; and

processing circuitry configured to determine the rotor position based on the inductive sense values and the stator winding voltage values.

13. Apparatus for determining rotor position as defined in claim 12, wherein the first circuitry is configured to measure inductive sense values by determining a time for a current through each pair of the stator windings to reach a current limit.

14. Apparatus for determining rotor position as defined in claim 12, wherein the second circuitry is configured to measure stator winding voltage values by determining if a winding voltage is positive or negative when a current is supplied through two other stator windings.

15. Apparatus for determining rotor position as defined in claim 12, wherein the processing circuitry is configured to determine the rotor position by accessing an entry in a table based on the inductive sense values and the stator winding voltage values.

16. Apparatus for determining rotor position as defined in claim 12, wherein the motor includes three stator windings and wherein the first circuitry is configured to measure six inductive sense values.

17. Apparatus for determining rotor position as defined in claim 12, wherein the motor includes three stator windings and wherein the second circuitry is configured to measure six stator winding voltage values.

18. Apparatus for determining rotor position as defined in claim 12, wherein the second circuitry is configured to measure stator winding voltage values by supplying a current through a pair of the stator windings and measuring a voltage across a third winding of the stator windings.

19. Apparatus for determining rotor position as defined in claim 18, wherein the second circuitry is configured to measure the voltage across the third winding by determining zero crossings of the voltage across the third winding.

20. Apparatus for determining rotor position as defined in claim 13, wherein the first circuitry is configured to determine the time to reach a current limit by sensing a voltage across a single sense resistor associated with the stator windings.

21. Apparatus for determining rotor position as defined in claim 13, wherein the second circuitry is configured to determine the time to reach the current limit by sensing a voltage across sense resistors associated with respective stator windings.