HVAC actuator with automatic end stop recalibration

• US 9,641,122 B2
• Filed: 12/29/2015
• Issued: 05/02/2017
• Est. Priority Date: 06/26/2012
• Status: Active Grant

• Current Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Romanowich, Gary A., Alexander, Robert K.
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US14/983,229
• Publication Number:
  US 20160156299A1
• Time in Patent Office: 490 Days
• Field of Search: 3184003, 318466, 318470, 318469, 31840009, 31840003, 31840004, 31840006, 31840012
• CPC Class Codes: F24F 2013/1433 with electric motors
• CPC Class Codes: H02H 7/0838 with H-bridge circuit
• CPC Class Codes: H02H 7/0852 directly responsive to abnormal temperature by using a temperature sensor in a control circuit H02H7/0833
• CPC Class Codes: H02P 27/085 wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage
• CPC Class Codes: H02P 29/027 the fault being an over-current
• CPC Class Codes: H02P 29/40 Regulating or controlling the amount of current drawn or delivered by the motor for controlling the mechanical load
• CPC Class Codes: H02P 29/60 Controlling or determining the temperature of the motor or of the drive H02P29/02 takes precedence
• CPC Class Codes: H02P 6/085 in a bridge configuration
• CPC Class Codes: H02P 6/17 and for generating speed information
• CPC Class Codes: H02P 6/24 Arrangements for stopping

Abstract

An actuator in a HVAC system includes a motor and a drive device driven by the motor. The drive device is coupled to a movable HVAC component for driving the movable HVAC component between multiple positions. The actuator further includes a main actuator controller. The main actuator controller includes end stop location memory that stores one or more end stop locations indicating expected locations of the one or more end stops. The main actuator controller further includes an end stop location recalibrator that runs an automatic recalibration process to determine and set recalibrated end stop locations. The end stop location recalibrator runs the automatic calibration process in response to detecting that the drive device has unexpectedly stalled at a location other than a stored end stop location.

Claims

1. An actuator in a HVAC system, the actuator comprising:

a motor;

a drive device driven by the motor and coupled to a movable HVAC component for driving the movable HVAC component between multiple positions bounded by one or more end stops; and

a main actuator controller comprising;

end stop location memory that stores one or more end stop locations indicating expected locations of the one or more end stops; and

an end stop location recalibrator that runs an automatic recalibration process to determine and set recalibrated end stop locations in response to detecting that the drive device has unexpectedly stalled at a location other than a stored end stop location.

2. The actuator of claim 1, wherein the drive device unexpectedly stalls prior to reaching a stored end stop location.

3. The actuator of claim 1, wherein the drive device proceeds through a stored end stop location and unexpectedly stalls at a location beyond the stored end stop location.

4. The actuator of claim 1, wherein the main actuator controller further comprises a stall detector that detects when the drive device has stalled and records the location of the drive device at stall.

5. The actuator of claim 4, wherein the main actuator controller further comprises a comparator that compares the stored end stop locations to the location of the drive device at stall and automatically initiates an automatic recalibration process in response to a determination that the location of the drive device at stall does not match any of the stored end stop locations.

6. The actuator of claim 1, wherein the main actuator controller further comprises a stroke respanner that calculates an adjusted stroke length of the actuator based on the recalibrated end stop locations.

7. The actuator of claim 6, wherein the main actuator controller further comprises a setpoint adjuster that receives an actuator position setpoint and adjusts the actuator position setpoint based on the adjusted stroke length.

8. The actuator of claim 1, further comprising one or more position sensors that measure a position of at least one of the drive device, the motor, and the movable HVAC component;

wherein the main actuator controller determines that the drive device is approaching an stored end stop location using feedback from the position sensors.

9. The actuator of claim 8, further comprising a threshold calculator that receives the stored end stop location from the end stop location memory and generates a soft stall threshold using the expected end stop location.

10. The actuator of claim 9, further comprising a comparator that compares the measured position with the soft stall threshold and generates a soft stall signal indicating the drive device is approaching the stored end stop location in response to the measured position reaching the soft stall threshold.

11. A method for controlling a HVAC actuator that includes a motor and a drive device driven by the motor and coupled to a movable HVAC component, the method comprising:

operating the motor to drive the movable HVAC component between multiple positions bounded by one or more end stops;

retrieving stored end stop locations from end stop location memory; and

automatically initiating an automatic calibration procedure to determine and set recalibrated end stop locations in response to detecting that the drive device has unexpectedly stalled at a location other than a stored end stop location.

12. The method of claim 11, further comprising detecting when the drive device unexpectedly stalls prior to reaching a stored end stop location.

13. The method of claim 11, further comprising detecting when the drive device proceeds through a stored end stop location and unexpectedly stalls at a location beyond the stored end stop location.

14. The method of claim 11, further comprising:

detecting that the drive device has encountered an unexpected end stop by determining when the drive device has stalled; and

recording the location of the drive device at stall.

15. The method of claim 14, further comprising comparing the stored end stop locations to the location of the drive device at stall and automatically initiating an automatic recalibration process in response to a determination that the locations do not match.

16. The method of claim 11, further comprising recalculating an adjusted stroke length of the actuator based on the recalibrated end stop locations.

17. The method of claim 16, further comprising receiving an actuator position setpoint and adjusting the actuator position setpoint input based on the adjusted stroke length.

18. The method of claim 11, further comprising using one or more position sensors to measure a position of at least one of the drive device, the motor, and the movable HVAC component;

wherein determining that the drive device is approaching the stored end stop location comprises using feedback from the position sensors.

19. The method of claim 18, further comprising using the location of the stored end stop to generate a soft stall threshold.

20. The method of claim 19, further comprising:

comparing the measured position with the soft stall threshold; and

generating a soft stall signal indicating that the drive device is approaching the stored end stop location in response to the measured position reaching the soft stall threshold.