US4438385A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic voltage regulation system for AC generator
Assignee: Hitachi Ltd
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Filing: 1982-05-20
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Granted: 1984-03-20
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Expires: 2002-05-20
Abstract
Abstract An output voltage of an AC generator is produced through a full-wave rectifier and converted into a digital signal by an A/D converter. This digital signal is compared with a reference signal, and in accordance with the difference therebetween, the firing angle of a thyristor is controlled to regulate the field current. Synchronous point detectors detect a synchronous point of the output voltage of the AC generator. A microprocessor computes a firing angle of the thyristor in accordance with the difference between the digital signal and the reference signal and produces a signal representing the computed firing angle upon detection of the synchronous point. The thyristor is fired at the firing angle computed by the microprocessor.
Inventors
- 👤 Hiroyasu Sato
- 👤 Kazuaki Yamamoto
- 👤 Hiroaki Aotsu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 08:31
CPC Classifications
G; G05; G05B; G05B15/00; G05B15/02; H; H02; H02P; H02P9/00; H02P9/14; H02P9/26; H02P9/30; H02P9/305
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
142 words
In an automatic voltage regulation system for an AC generator, having voltage detector means for detecting an output voltage of the AC generator and a thyristor for controlling the field current in accordance with the difference between a reference voltage and the voltage detected by said detector means, said automatic voltage regulation system further comprising: synchronous point detector means for detecting a synchronous point of the output voltage of said AC generator; a microprocessor for computing a firing angle of said thyristor in accordance with the difference between said reference voltage and the voltage detected by said voltage detector means and producing a signal representing the computed firing angle at the time of detection of the synchronous point; and firing control means for turning on said thyristor in response to the firing angle signal at the firing angle computed by said microprocessor.
Claim 2
Dependent Claim
142 words
In an automatic voltage regulation system for an AC generator, having voltage detector means for detecting an output voltage of the AC generator and a thyristor for controlling the field current in accordance with the difference between a reference voltage and the voltage detected by said detector means, said automatic voltage regulation system further comprising: synchronous point detector means for detecting a synchronous point of the output voltage of said AC generator; a microprocessor for computing a firing angle of said thyristor in accordance with the difference between said reference voltage and the voltage detected by said voltage detector means and producing a signal representing the computed firing angle at the time of detection of the synchronous point; and firing control means for turning on said thyristor in response to the firing angle signal at the firing angle computed by said microprocessor.
Claim 3
Dependent Claim
98 words
An automatic voltage regulation system for an AC generator according to claim 1, wherein said microprocessor is constructed in a manner that in the case where the voltage detected by said voltage detector means is within a predetermined range, said firing angle is computed by a transfer function including a lead-lag; in the case where said voltage is higher than said predetermined range, the firing angle is forcibly computed to a predetermined maximum value; and in the case where said voltage is lower than said predetermined range, the firing angle is computed forcibly to a predetermined minimum value.
Claim 4
Dependent Claim
66 words
An automatic voltage regulation system for an AC generator according to claim 1, wherein said synchronous point detector means includes a comparator for detecting the zero-crossing point of the interphase voltage of said AC generator as a synchronous point, and a programmable interrupt controller for generating an interrupt signal in response to a detection output of said comparator and applying said interrupt signal to said microprocessor.
Claim 5
Dependent Claim
66 words
An automatic voltage regulation system for an AC generator according to claim 1, wherein said firing control means includes a programmable timer for counting the time of the firing angle produced from said microprocessor and producing a pulse upon the lapse of said time, and a pulse transformer for amplifying the pulse of said programmable timer and applying said pulse to the gate of said thyristor.
Claim 6
Dependent Claim
42 words
An automatic voltage regulation system for an AC generator according to claim 1, wherein said AC generator is a three-phase AC generator and said comparator detects the zero-crossing point of one interphase voltage of said three-phase AC generator as a synchronous point.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-20 | 1987-09-19 | 1988-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-20 | 1991-09-19 | 1992-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-20 | 1995-09-19 | 1996-03-20 | $7700.00 | Window Closed / Lapsed |