Adaptive response time closed loop control algorithm

• US 7,603,186 B2
• Filed: 04/28/2006
• Issued: 10/13/2009
• Est. Priority Date: 04/28/2006
• Status: Active Grant

• Current Assignee: Hitachi Metals (Thailand) Ltd.
• Original Assignee: Advanced Energy Industries Incorporated
• Inventors: Smirnov, Alexei V.
• Primary Examiner(s): Masinick; Michael D
• Application Number:
  US11/413,780
• Publication Number:
  US 20070276545A1
• Time in Patent Office: 1,264 Days
• Field of Search: 700/28, 700/32, 700/37, 700/42, 700/282, 137/2, 137/486, 702/100
• US Class Current: 700/37
• CPC Class Codes: G05B 13/024 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: G05D 7/0635 by action on throttling means G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: Y10T 137/0324 With control of flow by a condition or characteristic of a fluid
• CPC Class Codes: Y10T 137/7759 Responsive to change in rate of fluid flow

Abstract

A system and method for controlling a flow of a fluid using an adaptive closed-loop-control algorithm is described. One embodiment includes a method for receiving a set point indicator and/or a sensor indicator generated by a sensor. A response time of a closed-loop-control algorithm is modified when at least one threshold value is satisfied based on the sensor indicator and/or the set point indicator. The closed-loop-control algorithm, which is implemented by a flow controller, is stabilized in response to the modifying of the response time of the closed-loop-control algorithm by adjusting at least one parameter associated with the closed-loop-control algorithm.

Claims

1. A method for adapting a response time of a mass flow controller while the mass flow controller is controlling flow of a fluid to a reaction vessel, comprising:

receiving a set point indicator, the set point indicator indicating a desired flow rate of the fluid;

receiving a sensor indicator generated by a sensor, the sensor indicator indicating a flow rate of the fluid being delivered to the vessel;

biasing the response time of a closed loop control algorithm to a slow mode;

briefly modifying the closed-loop-control algorithm to a fast mode when at least one threshold condition is satisfied based on the at least one of the sensor indicator or the set point indicator, the closed-loop-control algorithm affecting the rate which a valve in the mass flow controller changes position to provide the desired flow rate;

gradually modifying the closed-loop-control algorithm back to the slow mode;

stabilizing the closed-loop-control algorithm in response to the modifying the response time of the closed-loop-control algorithm by adjusting at least one parameter associated with the closed-loop-control algorithm.

2. The method of claim 1, further comprising detecting a change in the at least one of the sensor indicator or the set point indicator, the at least one threshold condition is satisfied by the change.

3. The method of claim 1, further comprising detecting a rate of change in the at least one of the sensor indicator or the set point indicator, the at least one threshold condition is satisfied by the rate of change.

4. The method of claim 1, wherein:

the at least one threshold condition is based on a flow rate error value, the flow rate error value is a difference between the fluid flow set point and the flow rate of the fluid.

5. The method of claim 1, wherein the accelerating or decelerating includes accelerating or decelerating in response to a change in a fluid flow rate through the flow controller and according to a mathematical equation.

6. The method of claim 1, wherein the modifying includes modifying at least one filter associated with the closed-loop-control algorithm.

7. The method of claim 1, wherein the modifying includes accelerating a response time of a feedback filter by adjusting a time constant associated with the feedback filter, the feedback filter being associated with the closed-loop-control algorithm.

8. The method of claim 1, wherein the at least one parameter is a tuning parameter associated with the closed-loop-control algorithm.

9. The method of claim 1, wherein the stabilizing includes stabilizing based on the at least one of the sensor indicator or the set point indicator.

10. The method of claim 1, wherein the closed-loop-control algorithm is based on at least one of proportional control, integral control, or derivative control.

11. The method of claim 1, wherein the sensor is at least one of a flow sensor, a timer, a pressure sensor or a temperature sensor.

12. A method for adapting a response time of a mass flow controller while the mass flow controller is controlling flow of a fluid to a processing vessel, comprising:

receiving a set point indicator, the set point indicator indicating a desired flow rate of the fluid;

receiving a sensor indicator generated by a sensor, the sensor indicator indicating a flow rate of the fluid being delivered to the vessel;

biasing the response time of a closed loop control algorithm to a slow mode;

modifying, while the mass flow controller is controlling flow of a fluid to a processing vessel, a feedback filter from a slow mode to a fast mode based on the at least one of the sensor indicator or the set point indicator, the feedback filter being associated with a closed-loop-control algorithm, the closed-loop-control algorithm being associated with a flow controller;

gradually modifying the feedback filter back to the slow mode; and

changing a tuning parameter associated with the closed-loop-control algorithm based on the modifying the feedback filter, the tuning parameter being changed to stabilize the closed-loop-control algorithm when the feedback filter is modified.

13. The method of claim 12, wherein the modifying the adaptive-gain based on the at least one of the sensor indicator or the set point indicator, the adaptive-gain is used in the closed-loop-control algorithm to compensate for at least one non-linear characteristic associated with the flow controller, the modifying the adaptive-gain includes modifying in response to a change in a fluid flow rate through the flow controller and according to a mathematical equation.

14. The method of claim 12, wherein the modifying the feedback filter includes modifying a response time associated with the feedback filter by adjusting a time constant associated with the feedback filter.

15. The method of claim 12, wherein the closed-loop-control algorithm is based on at least one of proportional control, integral control, or derivative control.

16. The method of claim 12, wherein the tuning parameter is associated with an integral control portion of the closed-loop-control algorithm.

17. The method of claim 12, wherein the sensor is at least one of a flow sensor, a timer, a pressure sensor or a temperature sensor.

18. The method of claim 12, wherein the modifying the feedback filter includes modifying in response to a change in a fluid flow rate through the flow controller and according to a mathematical equation.

19. The method of claim 12, wherein a response time of the closed-loop-control algorithm is different when the feedback filter is in the 4h4 fast mode than when the feedback filter is in the slow mode.

20. The method of claim 12, wherein the modifying the feedback filter includes modifying with reference to at least one threshold value associated with the at least one of the sensor indicator or the set point indicator.

21. The method of claim 12, wherein the gradually modifying the feedback filter includes gradually modifying the feedback filter in response to a change in a fluid flow rate through the flow controller and according to a mathematical equation.

22. A mass flow controller, comprising:

a processor configured to bias a response time of a closed loop control algorithm to a slow mode and to briefly modify the response time of the closed-loop-control algorithm from the slow mode to a fast mode when at least one threshold value is satisfied based on at least one of a sensor indicator generated by a sensor indicating a flow rate of a fluid being delivered to a processing vessel or a set point indicator indicating a desired flow rate of the fluid, the processor modifies the response time of the closed-loop-control algorithm by modifying a feedback filter associated with the closed-loop-control algorithm and a tuning parameter associated with the closed-loop-control algorithm, and the processor gradually modifies the closed-loop-control algorithm back to the slow mode; and

a memory configured to store a parameter associated with at least one of the feedback filter and the tuning parameter, the processor accesses the parameter from the memory.

23. The mass flow controller of claim 22, further comprising a valve configured to open and close in response to a control indicator, the control indicator being generated by the processor based on the closed-loop-control algorithm.

24. The mass flow controller of claim 22, wherein the sensor is at least one of a flow sensor, a timer, a pressure transducer or a temperature sensor.

25. The mass flow controller of claim 22, further comprising a memory that is configured to store the at least one threshold value, the processor is configured to access the at least one threshold value from the memory.