Systems and methods for back electromotive force based feedback for a movable component

• US 10,644,624 B1
• Filed: 12/27/2018
• Issued: 05/05/2020
• Est. Priority Date: 12/27/2018
• Status: Active Grant

• Current Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Viscardi, Claudio, Carozzi, Michele, Tamagni, Andrea, Lovati, Mattia
• Primary Examiner(s): Paul, Antony M
• Application Number:
  US16/234,001
• Time in Patent Office: 495 Days
• Field of Search: 3889281, 31840034, 31840001, 31840014, 31840032, 31840015, 318700, 318701, 318721, 318799, 318800, 318801, 318430, 318432, 702 64, 702 80
• CPC Class Codes: H02P 2203/03 Determination of the rotor position, e.g. initial rotor position, during standstill or low speed operation
• CPC Class Codes: H02P 6/182 using back-emf in windings

Abstract

Systems and methods for controlling a movable component using back electromotive force (BEMF)-based feedback are described. The system includes an actuator operatively coupled to the movable component. The actuator includes a motor for driving the movable component. The actuator includes a BEMF circuit for measuring a BEMF produced by the motor while driving the movable component. The system includes a processing circuit communicably coupled to the motor and the BEMF circuit. The processing circuit receives, from the BEMF circuit, a BEMF signal generated by the BEMF circuit as the motor drives the movable component. The processing circuit determines, based on the BEMF signal, an active range of the motor which corresponds to a full stroke of the movable component. The processing circuit controls the motor to drive the movable component within the active range.

Claims

1. A system for controlling a movable component in a building system using back electromotive force-based feedback, the system comprising:

an actuator operatively coupled to the movable component, the actuator comprising;

a motor configured to drive the movable component; and

a back electromotive force (BEMF) circuit configured to measure a BEMF produced by the motor while driving the movable component; and

a processing circuit communicably coupled to the motor and the BEMF circuit, the processing circuit comprising a processor and memory, the memory storing instructions that, when executed by the processor, cause the processor to perform operations comprising;

receiving, from the BEMF circuit, a BEMF signal generated by the BEMF circuit as the motor drives the movable component;

determining, based on the BEMF signal, an active range of the motor which corresponds to a full stroke of the movable component; and

controlling the motor to drive the movable component within the active range.

2. The system of claim 1, wherein determining the active range comprises:

identifying a first end point corresponding to a position of the motor as the motor begins to drive the movable component;

identifying a second end point based on a comparison of a mean BEMF to a sampled BEMF at the second end point; and

determining the active range, the active range being defined as spanning between the first end point and the second end point.

3. The system of claim 2, wherein identifying the first end point comprises identifying a hard stall position corresponding to the motor, the hard stall position being defined as a position in which the BEMF signal indicates zero BEMF.

4. The system of claim 2, wherein identifying the first end point comprises identifying a soft stall position corresponding to the motor, the soft stall position being defined as a position in which the BEMF signal indicates a BEMF value between zero and a threshold BEMF value.

5. The system of claim 1, wherein the active range of the motor is equal to the full stroke of the movable component.

6. The system of claim 1, wherein the motor has a range of motion larger than the active range of the motor.

7. The system of claim 1, wherein the operations further comprise:

identifying, while controlling the motor to drive the movable component within the active range, a BEMF value which is less than an expected BEMF value corresponding to a profile for the motor;

determining, based on the BEMF value being less than the expected BEMF value, that a sticking condition is present for the movable component; and

generating a signal corresponding to an alert for communication to an operator which indicates the sticking condition.

8. An actuator comprising:

a motor configured to drive a movable component configured to control one or more aspects of a system in a building;

a back electromotive force (BEMF) circuit configured to measure a BEMF produced by the motor while driving the movable component; and

a processing circuit communicably coupled to the motor and the BEMF circuit, the processing circuit comprising a processor and memory, the memory storing instructions that, when executed by the processor, cause the processor to perform operations comprising;

receiving, the BEMF circuit, a BEMF signal generated by the BEMF circuit as the motor drives the movable component;

determining, based on the BEMF signal, an active range of the motor which corresponds to a full stroke of the movable component; and

controlling the motor to drive the movable component within the active range.

9. The actuator of claim 8, wherein determining the active range comprises:

identifying a first end point corresponding to a position of the motor as the motor begins to drive the movable component;

identifying a second end point based on a comparison of a mean BEMF to a sampled BEMF at the second end point; and

determining the active range, the active range being defined as spanning between the first end point and the second end point.

10. The actuator of claim 9, wherein identifying the first end point comprises identifying a hard stall position corresponding to the motor, the hard stall position being defined as a position in which the BEMF signal indicates zero BEMF.

11. The actuator of claim 9, wherein identifying the first end point comprises identifying a soft stall position corresponding to the motor, the soft stall position being defined as a position in which the BEMF signal indicates a BEMF value between zero and a threshold BEMF value.

12. The actuator of claim 8, wherein the active range of the motor is equal to the full stroke of the movable component.

13. The actuator of claim 8, wherein the motor has a range of motion larger than the active range of the motor.

14. The actuator of claim 8, wherein the operations further comprise:

identifying, while controlling the motor to drive the movable component within the active range, a BEMF value which is less than an expected BEMF value corresponding to a profile for the motor;

determining, based on the BEMF value being less than the expected BEMF value, that a sticking condition is present for the movable component; and

generating a signal corresponding to an alert for communication to an operator which indicates the sticking condition.

15. A method for back electromotive force-based feedback, the method comprising:

receiving, from a back electromotive force (BEMF) circuit configured to measure a BEMF produced by a motor while a motor drives a movable component configured to control one or more aspects of a system in a building, a BEMF signal generated by the BEMF circuit as the motor drives the movable component;

determining, based on the BEMF signal, an active range of the motor which corresponds to a full stroke of the movable component; and

controlling the motor to drive the movable component within the active range.

16. The method of claim 15, wherein determining the active range comprises:

identifying a first end point corresponding to a position of the motor as the motor begins to drive the movable component;

identifying a second end point based on a comparison of a mean BEMF to a sampled BEMF at the second end point; and

determining the active range, the active range being defined as spanning between the first end point and the second end point.

17. The method of claim 16, wherein identifying the first end point comprises identifying one of a hard stall position and a soft stall position corresponding to the motor, the hard stall position being defined as a position in which the BEMF signal indicates zero BEMF and the soft stall position being defined as a position in which the BEMF signal indicates a BEMF value between zero and a threshold BEMF value.

18. The method of claim 15, wherein the active range of the motor is equal to the full stroke of the movable component.

19. The method of claim 15, wherein the motor has a range of motion larger than the active range of the motor.

20. The method of claim 15, further comprising:

identifying, while controlling the motor to drive the movable component within the active range, a BEMF value which is less than an expected BEMF value corresponding to a profile for the motor;

determining, based on the BEMF value being less than the expected BEMF value, that a sticking condition is present for the movable component; and

generating a signal corresponding to an alert for communication to an operator which indicates the sticking condition.