Adaptive predictive functional controller

• US 8,996,141 B1
• Filed: 08/26/2011
• Issued: 03/31/2015
• Est. Priority Date: 08/26/2010
• Status: Active Grant

• Current Assignee: Dunan Microstaq, Inc. (Zhejiang Dun'an Artificial Environment Co., Ltd.)
• Original Assignee: Dunan Microstaq, Inc. (Zhejiang Dun'an Artificial Environment Co., Ltd.)
• Inventors: Rao, Arvind, Alsaleem, Fadi
• Primary Examiner(s): SHECHTMAN, SEAN P
• Application Number:
  US13/199,363
• Time in Patent Office: 1,313 Days
• Field of Search: None
• US Class Current: 700/37
• CPC Class Codes: F16K 2099/0098 Refrigeration circuits, e.g. for cooling integrated circuits
• CPC Class Codes: F16K 99/0042 Electric operating means therefor
• CPC Class Codes: F24F 11/83 by controlling the supply of heat-exchange fluids to heat-exchangers
• CPC Class Codes: F24F 11/84 using valves
• CPC Class Codes: F25B 2339/047 Water-cooled condensers
• CPC Class Codes: F25B 2500/19 Calculation of parameters
• CPC Class Codes: F25B 2600/2513 Expansion valves
• CPC Class Codes: F25B 2700/197 of the evaporator
• CPC Class Codes: F25B 2700/21175 of the refrigerant at the outlet of the evaporator
• CPC Class Codes: F25B 40/02 Subcoolers
• CPC Class Codes: F25B 49/02 for compression type machines, plants or systems
• CPC Class Codes: G05B 13/048 using a predictor
• CPC Class Codes: G05D 7/0635 by action on throttling means G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: G05D 7/0694 by action on throttling means or flow sources of very small size, e.g. microfluidics microvalves F16K99/0001; microstructural devices per se B81B

Abstract

A controller device and a method for controlling a system that utilizes an adaptive mechanism to self-learn the system characteristics and incorporates this adaptive self-learning ability to predict a control parameter correctly to provide precise control of a system component.

Claims

1. A method for controlling a system comprising the steps of:

(a) providing at least one system component that is operational to control an operating parameter of the system;

(b) sensing at least one control parameter for the system component;

(c) determining the stability of the control parameter;

(d) adjusting, as needed, the control parameter as a function of the stability determination in step (c);

(e) developing a model for operation of the system that includes the control parameter; and

(f) utilizing the model developed in step (e) to tune a predictive controller, the predictive controller generating a control command for the system component, the control command including the at least one control parameter for the system component, wherein;

the system component is a valve that is operational to control the flow of a substance through a conduit, the conduit is included in a Heating, Ventilating and Air Conditioning (HVAC) system, the valve is a microvalve, and the control parameter is a superheat temperature set point.

2. The method according to claim 1 wherein steps (b) through (f) are repeated periodically.

3. The method according to claim 1 wherein steps (e) and (f) utilize a predictive adaptive controller.

4. The method according to claim 3 wherein the at least one control parameter included in the control command generated in step (f) includes at least one of a gain and a time constant.

5. The method according to claim 4 wherein the at least one control parameter included in the control command generated in step (f) includes both a gain and a time constant.

6. The method according to claim 5 wherein step (d) is carried out following a first time period and step (f) is carried out following a second time period with the second time period being less than the first period.

7. The method according to claim 6 wherein step (c) includes measuring the number of excursions outside an acceptable range for the set point during the first time period and further wherein, if the number of excursions outside the acceptable range exceeds a threshold, the at least one control parameter is increased.

8. The method according to claim 7 wherein step (c) further includes, upon the number of excursions outside the acceptable range for the set point being less that the threshold, continuing to measuring the number of excursions outside the acceptable range for the set point for a third time period that is greater than the second time period, and upon the number of excursions outside the acceptable range for the set point remaining less that the threshold, decreasing the at least one control parameter.

9. The method according to claim 8 wherein the threshold is a first threshold and, prior to step (b), the controller settings are initialized, and further wherein step (c) includes measuring the amount of time that the excursions of the set point are outside the acceptable range for the set point and, if the amount of time that excursions of the set point are outside the acceptable range for the at least one control parameter exceeds a second threshold, reinitializing the controller.

10. The method according to claim 9 wherein step (c) further includes measuring drift of the at least one control parameter relative to a drift threshold over a third time period that is greater than said first time period and, if the drift is greater than the drift threshold after the third time period expires, calibrating the model developed in step (d) accordingly.

11. The method according to claim 10 wherein the control command includes a pulse modulated wave with a variable duty cycle.

12. The method according to claim 1 wherein an array of microvalves is provided in step (a) and further wherein the control command generated in step (f) is applied to all of the microvalves in the array.

13. A device for controlling a system comprising:

at least one system component that is operational to control an operating parameter of the system;

at least one sensor mounted within the system, said sensor operative to sense a control parameter for said system component; and

a controller connected to said system component and said sensor, said controller being operative to monitor said at least one control parameter and to determine the stability of said control parameter, said controller also operative to adjust said control parameter, as needed, as a function of the stability determination and to develop a model for operation of the system that includes the control parameter, said controller further operative to utilize the model to tune a predictive controller, the predictive controller operative to generate a control command for the system component, the control command including the at least one control parameter for the system component, wherein;

the system component is a valve that is operational to control the flow of a substance through a conduit, the conduit is included in a Heating, Ventilating and Air Conditioning (HVAC) system, the valve is a microvalve, and the control parameter is a superheat temperature set point.

14. The device according to claim 13 wherein said controller is a predictive adaptive controller.

15. The device according to claim 14 wherein said control command includes at least one of a gain and a time constant.

16. A method for controlling a system comprising the steps of:

(a) providing at least one system component that is operational to control an operating parameter of the system;

(b) sensing at least one control parameter for the system component;

(c) determining the stability of the control parameter;

(d) adjusting, as needed, the at least one control parameter as a function of the stability determination in step (c);

(e) developing a model for operation of the system that includes the at least one control parameter; and

(f) utilizing the model developed in step (e) to tune a predictive controller, the predictive controller generating a control command for the system component, the control command including the at least one control parameter for the system component;

wherein;

steps (e) and (f) utilize a predictive adaptive controller;

the at least one control parameter included in the control command generated in step (f) includes at least one of a gain and a time constant;

step (d) is carried out following a first time period and step (f) is carried out following a second time period with the second time period being less than the first period;

step (c) includes measuring the number of excursions outside an acceptable range for the set point during the first time period and further wherein, if the number of excursions outside the acceptable range exceeds a threshold, the at least one control parameter is increased;

step (c) further includes, upon the number of excursions outside the acceptable range for the set point being less that the threshold, continuing to measuring the number of excursions outside the acceptable range for the set point for a third time period that is greater than the second time period, and upon the number of excursions outside the acceptable range for the set point remaining less that the threshold, decreasing the at least one control parameter;

the threshold is a first threshold and, prior to step (b), the controller settings are initialized, and further wherein step (c) includes measuring the amount of time that the excursions of the set point are outside the acceptable range for the set point and, if the amount of time that excursions of the set point are outside the acceptable range for the at least one control parameter exceeds a second threshold, reinitializing the controller;

step (c) further includes measuring drift of the control parameter relative to a drift threshold over a third time period that is greater than said first time period and, if the drift is greater than the drift threshold after the third time period expires, calibrating the model developed in step (d) accordingly;

the system component is a valve that is operational to control the flow of a substance through a conduit;

the conduit is included in a Heating, Ventilating and Air Conditioning (HVAC) system;

the valve is a microvalve; and

the at least one control parameter is a superheat temperature set point.

17. The method according to claim 16 wherein an array of microvalves is provided in step (a) and further wherein the control command generated in step (f) is applied to all of the microvalves in the array.