US3806784A
Expired / Lapsed
US
⏱️ 0.0 years remaining
A.c. power control unit
Assignee: Howden Supertherm Ltd
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Filing: 1972-12-04
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Granted: 1974-04-23
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Expires: 1992-12-04
Abstract
Abstract A method of controlling and a control unit for a system fed by an a.c. power through semiconductor power switches wherein a square wave is used to control firing pulses for the power switches, the mark-space ratio of the square wave being representative of an actual and a desired system parameter.
Inventors
- 👤 J Findlay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:07
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/12; G05F1/40; G05F1/44; G05F1/45; G05F1/452; G05D; G05D23/00; G05D23/19; G05D23/1906; G05D23/1913; G05D23/20; G05D23/24; H; H02; H02M; H02M1/00; H02M1/08; H02M1/083; H02P; H02P27/00; H02P27/02; H02P27/026
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
151 words
A method of controlling a system fed by an A.C. power supply through a semiconductor power switch in the power line, comprising the steps of: repetitively generating a staircase waveform, related in a known manner to the phase of the said power supply and in which each step of the staircase waveform has the same period as the power supply; generating a control signal being the sum of a signal representative of a desired system parameter and a signal representative of the difference between the desired system parameter and an actual system parameter; comparing the staircase waveform with the said control signal; generating a square wave having a mark-space ratio determined by the said comparison of the staircase waveform and the control signal: controlling the operation of a high frequency pulse generator with said square wave; and controlling the semiconductor power switch with the output of said high frequency pulse generator.
Claim 2
Independent Claim
151 words
A method of controlling a system fed by an A.C. power supply through a semiconductor power switch in the power line, comprising the steps of: repetitively generating a staircase waveform, related in a known manner to the phase of the said power supply and in which each step of the staircase waveform has the same period as the power supply; generating a control signal being the sum of a signal representative of a desired system parameter and a signal representative of the difference between the desired system parameter and an actual system parameter; comparing the staircase waveform with the said control signal; generating a square wave having a mark-space ratio determined by the said comparison of the staircase waveform and the control signal: controlling the operation of a high frequency pulse generator with said square wave; and controlling the semiconductor power switch with the output of said high frequency pulse generator.
Claim 3
Dependent Claim
19 words
The method as claimed in claim 1 wherein the number of steps of the staircase waveform is selectively variable.
Claim 4
Dependent Claim
140 words
A control unit for controlling a system fed by an a.c. power supply through a semiconductor switch in the power supply line, comprising a: square wave generator to generate a first squarewave having a known phase relationship with the power supply being controlled; a staircase waveform generator for generating a staircase waveform from the said first square wave; a control amplifier for generating a control signal being the sum of a signal representative of a desired system parameter and a signal representative of the difference between the desired system parameter and an actual system parameter; a difference amplifier for comparing the staircase waveform with the said control signal to generate a second square wave; and a firing pulse generator for activating the said semiconductor switch, the operation of the firing pulse generator being controlled by the said second square wave.
Claim 5
Dependent Claim
140 words
A control unit for controlling a system fed by an a.c. power supply through a semiconductor switch in the power supply line, comprising a: square wave generator to generate a first squarewave having a known phase relationship with the power supply being controlled; a staircase waveform generator for generating a staircase waveform from the said first square wave; a control amplifier for generating a control signal being the sum of a signal representative of a desired system parameter and a signal representative of the difference between the desired system parameter and an actual system parameter; a difference amplifier for comparing the staircase waveform with the said control signal to generate a second square wave; and a firing pulse generator for activating the said semiconductor switch, the operation of the firing pulse generator being controlled by the said second square wave.
Claim 6
Dependent Claim
18 words
A control unit as claimed in claim 3 wherein the components of the control unit are solid state.
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) | 1977-04-22 | 1977-10-22 | 1978-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-22 | 1981-10-22 | 1982-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-22 | 1985-10-22 | 1986-04-23 | $7700.00 | Window Closed / Lapsed |