Extremum seeking control with reset control

• US 8,666,517 B2
• Filed: 05/30/2012
• Issued: 03/04/2014
• 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): Padmanabhan, Kavita
• Assistant Examiner(s): Lin, Jason
• Application Number:
  US13/484,131
• Publication Number:
  US 20120239166A1
• Time in Patent Office: 643 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 the circuitry that implements the extremum seeking control strategy such that a performance gradient operated upon by the circuitry that implements the extremum seeking control strategy is forced to adjust faster than it would normally adjust given the abrupt operation of the plant, wherein the circuitry that implements the extremum seeking control strategy is configured to respond to the reset parameter by deactivating the extremum seeking control for a period of time;

wherein the reset parameter is provided for three to four times a dithering period of the extremum seeking control strategy and wherein the period of time during which the extremum seeking control is deactivated corresponds to the provision of the reset parameter.

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 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.

5. 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 generating a reset parameter which interrupts the extremum seeking control strategy operation, causing the extremum seeking control strategy to adapt to the performance gradient observed by the extremum seeking controller faster than the extremum seeking control strategy would normally adapt giving the abrupt operation of the plant, wherein the extremum seeking controller is configured to discontinue the extremum seeking control strategy for a period of time in response to receiving the reset parameter;

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.

6. The controller of claim 5, 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 duration of the reset parameter.

7. The controller of claim 5, 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.