Multi-mode control algorithm

• US 20080009978A1
• Filed: 07/05/2006
• Published: 01/10/2008
• Est. Priority Date: 07/05/2006
• Status: Active Grant

• Current Assignee: Hitachi Metals (Thailand) Ltd.
• Original Assignee: Advanced Energy Industries Incorporated
• Inventors: Smirnov, Alexei V.
• Granted Patent: US 7,640,078 B2
• Time in Patent Office: Days
• US Class Current: 700/282
• CPC Class Codes: G05D 7/0635 by action on throttling means G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: Y10T 137/0379 By fluid pressure

Abstract

A system and method for controlling a flow of a fluid using a multi-mode control algorithm is described. One embodiment includes a method for changing the multi-mode control algorithm from a closed-loop mode to an open-loop mode. The method includes receiving at least one sensor indicator generated by a sensor. The multi-mode control algorithm is modified from the closed-loop mode to the open-loop mode when, based on the at least one sensor indicator, the threshold condition is satisfied. The multi-mode control algorithm is used by a flow controller to control a flow of a fluid according to a set point.

Claims

1. A method, comprising:

receiving a pressure measurement of a fluid generated by a pressure sensor; and

calculating a valve position based on the pressure measurement when a feedback control loop has been disengaged, the feedback control loop being disengaged when a pressure change of a fluid satisfies a threshold condition, the valve being used to control a flow of the fluid.

2. The method of claim 1, wherein the feedback control loop is configured to control the flow of the fluid according to a set point and based on a characteristic of the flow as provided by a sensor.

3. The method of claim 1, wherein the feedback control loop is configured to control the flow of the fluid using a flow sensor that senses the flow of the fluid, the threshold condition is defined based on a characteristic of the flow sensor.

4. The method of claim 1, wherein the feedback control loop is configured to control the flow of the fluid using a flow sensor that senses the flow of the fluid, the threshold condition is defined based on an operating range of the flow sensor.

5. The method of claim 1, wherein the controlling includes calculating the valve position based on at least one of calibration data or characterization data.

6. The method of claim 1, further comprising re-engaging the feedback control loop when at least one of a time period of a timer expires or the threshold condition changes from being satisfied to unsatisfied.

7. The method of claim 1, further comprising re-engaging the feedback control loop when a time period of a timer expires, the time period is defined based on a magnitude of the pressure change.

8. The method of claim 1, wherein the pressure change is a pressure change rate that is calculated using at least two measurements each with a corresponding measurement time.

9. The method of claim 1, wherein the pressure measurement is a second pressure measurement at a second time,

the method, further comprising detecting the pressure change of the fluid, the pressure change is a difference between a first pressure measurement at a first time and the second pressure measurement, the second time is after the first time.

10. The method of claim 1, the threshold condition is a first threshold condition,

the method, further comprising re-engaging the feedback control loop when a second threshold condition is satisfied.

11. The method of claim 1, wherein the pressure measurement is a first pressure measurement at a first time, the threshold condition is a first threshold condition,

the method, further comprising re-engaging the feedback control loop when a time period of a timer expires, a duration of the time period is modified when a magnitude of a difference between a second pressure measurement at a second time and the first pressure measurement at the first time satisfies at least one of the first threshold condition or a second threshold condition.

12. A method, comprising:

receiving at least one sensor indicator generated by a sensor; and

modifying a multi-mode control algorithm from a closed-loop mode to an open-loop mode when, based on the at least one sensor indicator, a threshold condition is satisfied, the multi-mode control algorithm is used by a flow controller to control a flow of a fluid according to a set point.

13. The method of claim 12, further comprising calculating, using the open-loop mode and using the at least one sensor indicator, a valve position of a valve so as to deliver the fluid according to the set point.

14. The method of claim 12, further comprising calculating, using the open-loop-control algorithm and using the at least one sensor indicator, a valve position of a valve so as to deliver the fluid according to the set point, the valve position is calculated based on a mathematical relationship.

15. The method of claim 12, wherein the sensor is a pressure sensor, the at least one sensor indicator is a pressure sensor indicator.

16. 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.

17. The method of claim 12, further comprising detecting a change in the sensor indicator, the threshold condition is satisfied by the change.

18. The method of claim 12, wherein the sensor indicator indicates a characteristic associated with the fluid.

19. The method of claim 12, wherein the closed-loop mode is configured to control the flow of the fluid using a flow sensor that senses the flow of the fluid, the threshold condition is defined based on at least one of a characteristic of the flow sensor or an operating range of the flow sensor.

20. The method of claim 12, further comprising modifying the control algorithm from the open-loop mode to the closed-loop mode when a time period of a timer expires.

21. The method of claim 12, further comprising modifying the control algorithm from the open-loop mode to the closed-loop mode when the threshold condition associated with the sensor indicator changes from being satisfied to unsatisfied.

22. The method of claim 12, wherein the threshold condition is a first threshold condition, the at least one sensor indicator is received at a first time.

the method further comprising modifying the control algorithm from the open-loop mode to the closed-loop mode when, based on a second sensor indicator received at a second time from the sensor, a second threshold condition is satisfied.

23. The method of claim 12, wherein the open-loop mode is selected from a set of open-loop modes in response to the threshold condition being satisfied.

24. An apparatus, comprising:

a processor configured to calculate a valve position based on a pressure measurement when a feedback control loop has been disengaged, the feedback control loop being disengaged when a pressure change of a fluid satisfies a threshold condition, a valve controls a flow of the fluid in response to the valve position; and

a memory configured to store a mathematical relationship between the valve position, the flow of the fluid, and the pressure measurement, the mathematical relationship is used by the processor to calculate the valve position.

25. The apparatus of claim 24, further comprising a memory that is configured to store the threshold condition, the processor is configured to access the threshold condition from the memory.

26. The apparatus of claim 24, wherein the feedback control loop is configured to control the flow of the fluid according to a set point and using a flow sensor that senses the flow of the fluid, the threshold condition is defined based on an operating range of the flow sensor.

27. The apparatus of claim 24, wherein the feedback control loop is re-engaged when at least one of a time period of a timer expires or the threshold condition changes from being satisfied to unsatisfied.