US3790764A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Time delay compensation in a closed loop process control system
Assignee: Cegelec SA
•
Filing: 1971-12-23
•
Granted: 1974-02-05
•
Expires: 1991-12-23
Abstract
Abstract The deleterious effect of time lag in an industrial process on the operation of a closed loop feedback control system in which such process is regulated may be substantially eliminated without sacrificing static accuracy of the system by a specially designed process controller. The controller includes first and second networks connected in tandem in the main path of the feedback loop through one input of a first subtracter. The controller output is coupled to one input of a second subtracter through a third network whose transfer function is equal to the product of the first network transfer function and the equivalent unretarded transfer function of the controlled process. The output of the third network is also coupled to the other input of the second substracter through a retardation circuit having the same delay characteristics as that of the process. The output of the second subtracter is connected to the second input of the first subtracter to provide the required process control signal at the output of the second network.
Inventors
- 👤 R Rouxel
- 👤 G Chevalier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:35
CPC Classifications
G; G05; G05B; G05B21/00; G05B21/02; G05B6/00; G05B6/02
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
310 words
In a closed-loop control system including a controller regulating a time-retarded process having an effective transfer function F X G, where G represents an equivalent unretarded transfer function of the process and F represents the retardation factor, an improved controller arrangement for eliminating the effect of process time delay from the closed loop system, which comprises: first and second subtracting means each having first and second inputs; a first network for coupling the input terminal of the controller to a first input of the first subtracting means; a second network having a transfer function equal to the product of G and the transfer function of the first network for coupling the output terminal of the controller to the first input of the second subtracting means; a retardation circuit having the transfer function F for coupling the output of the second network to the second input of the second subtracting means; means for applying the output of the second subtracting means to the second input of the first subtracting means; means for transferring the output of the first subtracting means to the output terminal of the controller; the transfer function G being of the form K0 divided by (1 + pT0); the first network comprising means for generating a first signal proportional by a factor 1 divided by K0 to a signal appearing at the controller input terminal; and the second network comprising, in combination, means for generating a second signal proportional by a factor 1 divided by pT0 to a signal applied thereto; third subtracting means; first means for connecting the second network output to the first input of the third subtracting means; means for applying the output of the third subtracting means to the input of the second signal generating means; and means for coupling the output terminal of the controller to the input of the third subtracting means.
Claim 2
Dependent Claim
310 words
In a closed-loop control system including a controller regulating a time-retarded process having an effective transfer function F X G, where G represents an equivalent unretarded transfer function of the process and F represents the retardation factor, an improved controller arrangement for eliminating the effect of process time delay from the closed loop system, which comprises: first and second subtracting means each having first and second inputs; a first network for coupling the input terminal of the controller to a first input of the first subtracting means; a second network having a transfer function equal to the product of G and the transfer function of the first network for coupling the output terminal of the controller to the first input of the second subtracting means; a retardation circuit having the transfer function F for coupling the output of the second network to the second input of the second subtracting means; means for applying the output of the second subtracting means to the second input of the first subtracting means; means for transferring the output of the first subtracting means to the output terminal of the controller; the transfer function G being of the form K0 divided by (1 + pT0); the first network comprising means for generating a first signal proportional by a factor 1 divided by K0 to a signal appearing at the controller input terminal; and the second network comprising, in combination, means for generating a second signal proportional by a factor 1 divided by pT0 to a signal applied thereto; third subtracting means; first means for connecting the second network output to the first input of the third subtracting means; means for applying the output of the third subtracting means to the input of the second signal generating means; and means for coupling the output terminal of the controller to the input of the third subtracting means.
Claim 3
Dependent Claim
92 words
A system as defined in claim 1, in which the transferring means comprises, in combination, means for generating a third signal proportional by a factor Q to the output of the first subtracting means; means for generating a fourth signal proportional by a factor Q Divided by pT0 to the output of the first subtracting means; first adding means; means for applying the third and fourth signals to the respective inputs of the first adding means; and means for coupling the output of the first adding means to the controller output terminal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-04 | 1977-08-06 | 1978-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-04 | 1981-08-06 | 1982-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-04 | 1985-08-06 | 1986-02-05 | $7700.00 | Window Closed / Lapsed |