Extremum seeking control with reset control

• US 8,200,344 B2
• Filed: 12/30/2009
• Issued: 06/12/2012
• Est. Priority Date: 07/17/2007
• Status: Active Grant

• Current Assignee: Tyco Fire & Security GmbH (Johnson Controls International plc)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Li, Yaoyu, Seem, John E.
• Primary Examiner(s): Decady, Albert
• Assistant Examiner(s): Lin, Jason
• Application Number:
  US12/650,366
• Publication Number:
  US 20100106328A1
• Time in Patent Office: 895 Days
• Field of Search: 700 28- 34, 700/38, 700/275, 700/276, 700/299, 700/300, 714/39, 714/E11.024
• US Class Current: 700/38
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: G05B 13/024 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 5/01 electric

Abstract

An extremum seeking control method optimizes a control process for a plant such as an air handling unit. The method compensates for abrupt changes in the operation of the plant by resetting the extremum seeking control strategy in response to a detection of the abrupt change.

Claims

1. A method for optimizing a control process for a plant, the method comprising:

operating the plant using circuitry that implements an extremum seeking control strategy;

detecting an abrupt change in the operation of the plant; and

using a circuit to compensate for the abrupt change in the operation of the plant by resetting the extremum seeking control strategy;

wherein resetting the extremum seeking control strategy comprises providing a reset parameter to a high-pass filter of the circuitry that implements the extremum seeking control strategy such that a performance gradient that is probed for using the high-pass filter is forced to change faster than it would normally change given the abrupt operation of the plant.

2. The method of claim 1, wherein detecting an abrupt change in the operation of the plant comprises:

detecting a change of greater than or equal to two percent in the performance of the plant within a defined time period.

3. The method of claim 1, further comprising:

retrieving historical data on one or more optimum plant settings previously determined by the extremum seeking control strategy from memory; and

using the historical data to determine the reset parameter.

4. The method of claim 1, wherein the reset parameter is provided for three to four times a dithering period of the extremum seeking control strategy.

5. The method of claim 1, wherein the plant is an air handling unit configured to regulate temperature and controlled by a controller configured to provide a control signal to a temperature regulator, wherein the air handling unit also includes a damper controlled by an actuator, and wherein the extremum seeking control strategy is used to operate the actuator.

6. A controller for controlling a plant, the controller comprising:

a circuit configured to operate the plant using an extremum seeking control strategy, the circuit configured to detect an abrupt change in the operation of the plant and the circuit further configured to compensate for the abrupt change by resetting the extremum seeking control strategy, wherein resetting the extremum seeking control strategy comprises providing a reset parameter to a high-pass filter used by the circuit to probe for a performance gradient of the extremum seeking control strategy, the reset parameter applied to the high-pass filter such that the performance gradient observed by the extremum seeking controller is forced to change faster than it would normally change given the abrupt operation of the plant.

7. The controller of claim 6, wherein the circuit is further configured to retrieve historical data of one or more optimum plant settings previously determined by the extremum seeking control strategy from memory, and wherein the circuit is configured to use the historical data to determine the reset parameter.

8. The controller of claim 6, wherein the plant is an air handling unit configured to regulate temperature and controlled by a controller configured to provide a control signal to a temperature regulator, wherein the air handling unit also includes a damper controlled by an actuator, and wherein the extremum seeking control strategy is used to operate the actuator.

9. The controller of claim 6, wherein the circuit is further configured to provide the reset parameter to the extremum seeking control strategy for at least three times a dithering period of the extremum seeking control strategy.

10. The controller of claim 6, wherein the reset parameter overrides the measurement received from the plant and used by the extremum seeking control strategy.

11. A controller for an air handling unit having an actuator that opens and closes a damper to control the amount of outdoor air used for cooling the air provided to a building space by the air handling unit, comprising:

an input interface configured to receive a temperature sensor input;

a temperature regulator control module configured to provide a command to a temperature regulator system configured to controllably chill air provided by the air handling unit, wherein the temperature regulator control module determines the command based on the temperature sensor input received at the input interface;

an extremum seeking control module configured to receive the command from the temperature regulator control module and comprising logic configured to use the command to calculate one or more parameters of a signal estimated to cause the damper to be positioned to maximize the use of outdoor air used for cooling the air provided by the air handling unit;

an output interface configured to provide the signal to the actuator for the damper according to the parameter or parameters calculated by the extremum seeking control module;

a reset control module;

a change detection module configured to determine when an abrupt change in the command has occurred and to provide the determination to the reset control module;

wherein the reset control module is configured to respond to the determination that an abrupt change has occurred by providing an output to the extremum seeking control module that is configured to eliminate or reduce a response by the extremum seeking control module to the abrupt change in the command.

12. The controller of claim 11, wherein the reset control module is configured to provide the output to the extremum seeking control module by overriding the command provided from the temperature regulator control module to the extremum seeking control module.

13. The controller of claim 12, wherein the reset control module is configured to hold the overriding of the command for a period of time prior to allowing the extremum seeking control module to resume using the command from the temperature regulator control module.

14. The controller of claim 13, wherein the reset control module is configured to select the magnitude of the override based on historical values of the command received prior to the detection of the abrupt change.