US3840798A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power supply devices
Assignee: Individual
•
Filing: 1973-04-30
•
Granted: 1974-10-08
•
Expires: 1993-04-30
Abstract
Abstract A power supply for producing a.c. power at low voltage from conventional a.c. supply mains, without heavy-duty mains transformers. The supply is rectified, and switched at high frequency, transformed to low or other voltage and rectified. Control of the switching means is by comparison of voltage ramps with a threshold voltage and the threshold voltage is controlled in accordance with variables including voltage and current output, to vary the duty cycle of the switching means and hence the output.
Inventors
- 👤 J Crowe
- 👤 N Brand
- 👤 I Bland
- 👤 T Cryer
- 👤 R Thompson
- 👤 M Burchall
- 👤 D Copplestone
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:47
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/337; H02M3/3376
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
302 words
A power supply apparatus for providing a direct current output from an alternating current input, comprising rectifying means for rectifying an alternating current input to produce a rectified output; semiconductor switching means for switching said rectified input; a transformer having input and output terminals; means for applying the switched rectified current alternately in effectively opposite polarity to the transformer input terminals to produce at the transformer output terminals an alternating current output; a second rectifying means for rectifying said alternating current output to produce a direct current output, the frequency of said alternating current output being substantially greater than frequency of said alternating current input; control means for controlling the switching of said semiconductor switching means, said control means including ramp voltage generator means for producing two ramp voltage trains of which the respective ramp voltages alternate in time; a threshold voltage source; a constant current source; first, second and third transistors through which in parallel current from said constant current source is arranged to pass; conductor means for impressing on said first and second transistors said ramp voltage trains, respectively, whereby said first and second transistors are rendered alternatively conductive; and conductor means for applying voltage from said threshold voltage source to said third transistor to control current in said third transistor in accordance with said threshold voltage, whereby one of said first and second transistors passes current for a period dependent upon the voltage of said ramp voltage applied thereto and upon said threshold voltage, and said control means controls said switching means in accordance with the period during which said first and second transistors pass current, whereby to control the period during which rectified current is fed to the transformer input, said threshold voltage source varying said threshold voltage in accordance with a condition of said direct current input.
Claim 2
Dependent Claim
302 words
A power supply apparatus for providing a direct current output from an alternating current input, comprising rectifying means for rectifying an alternating current input to produce a rectified output; semiconductor switching means for switching said rectified input; a transformer having input and output terminals; means for applying the switched rectified current alternately in effectively opposite polarity to the transformer input terminals to produce at the transformer output terminals an alternating current output; a second rectifying means for rectifying said alternating current output to produce a direct current output, the frequency of said alternating current output being substantially greater than frequency of said alternating current input; control means for controlling the switching of said semiconductor switching means, said control means including ramp voltage generator means for producing two ramp voltage trains of which the respective ramp voltages alternate in time; a threshold voltage source; a constant current source; first, second and third transistors through which in parallel current from said constant current source is arranged to pass; conductor means for impressing on said first and second transistors said ramp voltage trains, respectively, whereby said first and second transistors are rendered alternatively conductive; and conductor means for applying voltage from said threshold voltage source to said third transistor to control current in said third transistor in accordance with said threshold voltage, whereby one of said first and second transistors passes current for a period dependent upon the voltage of said ramp voltage applied thereto and upon said threshold voltage, and said control means controls said switching means in accordance with the period during which said first and second transistors pass current, whereby to control the period during which rectified current is fed to the transformer input, said threshold voltage source varying said threshold voltage in accordance with a condition of said direct current input.
Claim 3
Dependent Claim
90 words
A power supply apparatus as claimed in claim 1, and comprising means for feeding current from said first and second transistors to said respective semiconductor switching means to cause said switching means to conduct, a fourth transistor coupled to the output of said first and second transistors to terminate pulses from said first and second transistors and thereby reduce said semiconductor switching means to non-conduction, and circuit means for controlling said fourth transistor in accordance with the duration of the periods during which said first and second transistors pass current.
Claim 4
Dependent Claim
57 words
A power supply apparatus as claimed in claim 2, wherein said semiconductor switching means each comprises a switching transistor, and wherein said fourth transistor is arranged to impose a low impedance across an input of said semiconductor switching transistors whereby to extract reverse base current from said transistors to effect rapid turn off to the non-conducting condition.
Claim 5
Dependent Claim
91 words
A power supply apparatus as claimed in claim 1, and comprising current sensing means producing an output responsive to a current which is a function of output current of said apparatus, a current sensing control transistor the current in which is responsive to the output current of said current sensing means, said sensing control transistor current being arranged to modify the said constant current shared by said first, second and third transistors whereby to control the switching of said semiconductor switching means as a function of output current from said apparatus.
Claim 6
Dependent Claim
25 words
A power supply apparatus as claimed in claim 4, and comprising capacitor delay means for delaying the response of said apparatus to said output current.
Claim 7
Dependent Claim
52 words
A power supply apparatus as claimed in claim 4, wheRein said current sensing means is a current transformer having first and second windings through the first of which passes current switched by said switching means and including a rectifier device for rectifying voltage produced at the second winding of said current transformer.
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) | 1977-10-07 | 1978-04-08 | 1978-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-07 | 1982-04-08 | 1982-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-07 | 1986-04-08 | 1986-10-08 | $7700.00 | Window Closed / Lapsed |