US4806836A
Expired / Lapsed
US
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Anti-reset windup for controllers in selective control loops
Assignee: Applied Automation Inc
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Filing: 1988-01-14
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Granted: 1989-02-21
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Expires: 2008-01-14
Abstract
Abstract A tuning adjustment for a PI controller is disclosed which produces a desired response for a controlled variable in a selective control loop having an external reset feedback signal for anti-reset-windup protection. The desired control effect is evident in the time response of the controlled variables return to set point when a select switches signals and suddenly selects an output limited PI controller to control a process variable, and the selected controller assumes control of the process variable starting with its output at the limiting value. The tuning adjustment is implemented by combining the signal selected for controlling the process variable and a tuning factor for use as the reset feedback signal for the PI controller.
Inventors
- 👤 Don W. Webb
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:30
CPC Classifications
G; G05; G05B; G05B5/00; G05B5/01
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
188 words
Apparatus comprising: controller means for automatically generating an output signal in response to an error signal representative of the deviation of a processs variable signal from a set point and of the time integral of said error signal, wherein said output signal includes an integral part and a proportional part and wherein said controller means includes an external reset signal input; means for selecting a signal from a group of signals, which includes said output signal, to establish a selected signal wherein said selected signal is provided to a control element for said process variable; means for establishing an anti-reset-windup (ARW) tuning signal representative of a desired tuning factor; means for modifying said selected signal responsive to said ARW tuning signal to establish an adjustable reset feedback signal, wherein said selected signal provided to said control element is unaffected by said means for modifying said selected signal; and means for providing said adjustable reset feedback signal to said external feedback input of said controller means, wherein said integral part of said output signal responds to said adjustable reset feedback signal in addition to responding to said error signal.
Claim 2
Dependent Claim
188 words
Apparatus comprising: controller means for automatically generating an output signal in response to an error signal representative of the deviation of a processs variable signal from a set point and of the time integral of said error signal, wherein said output signal includes an integral part and a proportional part and wherein said controller means includes an external reset signal input; means for selecting a signal from a group of signals, which includes said output signal, to establish a selected signal wherein said selected signal is provided to a control element for said process variable; means for establishing an anti-reset-windup (ARW) tuning signal representative of a desired tuning factor; means for modifying said selected signal responsive to said ARW tuning signal to establish an adjustable reset feedback signal, wherein said selected signal provided to said control element is unaffected by said means for modifying said selected signal; and means for providing said adjustable reset feedback signal to said external feedback input of said controller means, wherein said integral part of said output signal responds to said adjustable reset feedback signal in addition to responding to said error signal.
Claim 3
Dependent Claim
74 words
Apparatus in accordance with claim 1 wherein said means for modifying said selected signal to establish an adjustable reset feedback signal comprises: means for establishing a first signal representative of the deviation of said output signal from said selected signal; means for dividing said first signal by said ARW tuning signal to establish a second signal; and means for summing said second signal and said output signal to establish said adjustable reset feedback signal.
Claim 4
Dependent Claim
20 words
Apparatus in accordance with claim 2 wherein said ARW tuning signal is representative of a number between zero and unity.
Claim 5
Dependent Claim
17 words
Apparatus in accordance with claim 1 wherein said means for selecting a signal is a high select.
Claim 6
Dependent Claim
17 words
Apparatus in accordance with claim 1 wherein said means for selecting a signal is a low select.
Claim 7
Dependent Claim
21 words
Apparatus in accordance with claim 1 wherein said process variable signal is representative of the solids concentration in a polymerization reaction.
Claim 8
Dependent Claim
21 words
Apparatus in accordance with claim 1 wherein said process variable signal is representative of a measured pressure rise across a compressor.
Claim 9
Independent Claim
204 words
A method for obtaining a desired response for a controlled variable in a selective control loop wherein a selected signal is provided to a control element to control a process variable and wherein a select switches signals and suddenly selects an output signal of a PI controller to control said process variable, said output signal having a proportional part and an integral part responsive to an error signal, said PI controller having an external reset feedback input, and wherein said output signal is at a limiting value when selected by said select, said method comprising the following steps which are performed prior to selecting said output signal of said PI controller to control said process variable: establishing an anti-reset-windup (ARW) tuning signal representative of a desired tuning factor; modifying said selected signal responsive to said ARW tuning signal to establish an adjustable reset feedback signal, wherein said selected signal provided to said control element is unaffected by said step of modifying said selected signal; and providing said adjustable reset feedback signal to said external reset signal input of said PI controller, wherein said integral part of said output signal responds to said adjustable reset feedback signal in addition to responding to said error signal.
Claim 10
Independent Claim
204 words
A method for obtaining a desired response for a controlled variable in a selective control loop wherein a selected signal is provided to a control element to control a process variable and wherein a select switches signals and suddenly selects an output signal of a PI controller to control said process variable, said output signal having a proportional part and an integral part responsive to an error signal, said PI controller having an external reset feedback input, and wherein said output signal is at a limiting value when selected by said select, said method comprising the following steps which are performed prior to selecting said output signal of said PI controller to control said process variable: establishing an anti-reset-windup (ARW) tuning signal representative of a desired tuning factor; modifying said selected signal responsive to said ARW tuning signal to establish an adjustable reset feedback signal, wherein said selected signal provided to said control element is unaffected by said step of modifying said selected signal; and providing said adjustable reset feedback signal to said external reset signal input of said PI controller, wherein said integral part of said output signal responds to said adjustable reset feedback signal in addition to responding to said error signal.
Claim 11
Dependent Claim
70 words
A method in accordance with claim 8 wherein said step of modifying said selected signal to establish an adjustable reset feedback signal comprises: establishing a first signal representative of the deviation of said output signal from said selected signal; dividing said first signal by said ARW tuning signal to establish a second signal representative; and summing said second signal and said output signal to establish said adjustable reset feedback signal.
Claim 12
Dependent Claim
21 words
A method in accordance with claim 9 wherein said ARW tuning signal is representative of a number between zero and unity.
Claim 13
Dependent Claim
14 words
A method in accordance with claim 8 wherein said select is a high select.
Claim 14
Dependent Claim
14 words
A method in accordance with claim 8 wherein said select is a low select.
Claim 15
Dependent Claim
21 words
A method in accordance with claim 8 wherein said process variable is representative of the solids concentration is a polymerization reaction.
Claim 16
Dependent Claim
21 words
A method in accordance with claim 8 wherein said process variable is representative of a measured pressure rise across a compressor.
References Cited (Backward Citations)
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| 3.5 Years (Year 4) | 1992-02-21 | 1992-08-22 | 1993-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-21 | 1996-08-22 | 1997-02-21 | $3760.00 | Window Closed / Lapsed |
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