Patent US953175A successfully refreshed from Google Patents.
US3663941A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dc to ac to dc converter having transistor synchronous rectifiers
Assignee: National Aeronautics and Space Administration
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Filing: 1970-12-16
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Granted: 1972-05-16
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Expires: 1990-12-16
Abstract
Abstract A DC to AC inverter including a pair of transistors driven in push-pull by means of coupling through first and second transformers, each having a saturable core, drives a DC load through a synchronous rectifier. The synchronous rectifier includes a pair of transistors, the emitter collector junctions of which are driven with the same waveshape as the emitter base junctions of the inverter. A circuit connecting the two transformers together includes a saturable reactor, whereby the base drive for the transistors of the inverter and the synchronous rectifier is a waveform having two relatively steep transitions in opposite directions at the moment of switch on to remove charge stored on the bases and a further relatively steep transition prior to cut off to minimize charge stored on the bases during conducting intervals of the transistors.
Inventors
- 👤 Edward R Pasciutti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:32
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/338; H02M3/3382; H02M3/3384
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
310 words
In combination with a DC to AC inverter including, a pair of transistors driving a first transformer having a core, positive feedback means for coupling said first transformer to a second transformer driving said pair of transiStors alternately into and out of conduction, said means for coupling including a frequency determining circuit including a saturable reactor and an inductor, whereby there is derived in a secondary winding of the second transformer a periodic waveform, said waveform including, during each period thereof, first, second and third relatively steep transitions, said first and second transitions following each other in rapid succession, said second and third transitions being directed in the same direction opposite from that of the first transitions, said second and third transitions being followed by a relatively flat wave segment, the flat wave segment following the third transitions being in turn followed by the first transition, means coupling replicas of said waveform to base electrodes of said transistors to drive the transistors in push-pull relationship; an AC to DC synchronous rectifier for feeding power from the first transformer to a load, the improvement comprising: a pair of transistors forming synchronous switch means in said rectifier, each transistor of said switch means having base electrode control means and an emitter collector path for feeding power from the first transformer means to the load, means coupled to secondary winding means of said second transformer for driving said base electrodes of each transistor of the switch means with replicas of said periodic waveforms, the replicas driving the base electrodes of the transistor of the switch means being displaced by 180*, whereby the first transitions have a tendency to drive nonconducting transistors of the inverter and switch means to a conducting state, and the third transitions and the following flat wave segments cut off conducting transistors of the inverter and switch means without overlap.
Claim 2
Dependent Claim
310 words
In combination with a DC to AC inverter including, a pair of transistors driving a first transformer having a core, positive feedback means for coupling said first transformer to a second transformer driving said pair of transiStors alternately into and out of conduction, said means for coupling including a frequency determining circuit including a saturable reactor and an inductor, whereby there is derived in a secondary winding of the second transformer a periodic waveform, said waveform including, during each period thereof, first, second and third relatively steep transitions, said first and second transitions following each other in rapid succession, said second and third transitions being directed in the same direction opposite from that of the first transitions, said second and third transitions being followed by a relatively flat wave segment, the flat wave segment following the third transitions being in turn followed by the first transition, means coupling replicas of said waveform to base electrodes of said transistors to drive the transistors in push-pull relationship; an AC to DC synchronous rectifier for feeding power from the first transformer to a load, the improvement comprising: a pair of transistors forming synchronous switch means in said rectifier, each transistor of said switch means having base electrode control means and an emitter collector path for feeding power from the first transformer means to the load, means coupled to secondary winding means of said second transformer for driving said base electrodes of each transistor of the switch means with replicas of said periodic waveforms, the replicas driving the base electrodes of the transistor of the switch means being displaced by 180*, whereby the first transitions have a tendency to drive nonconducting transistors of the inverter and switch means to a conducting state, and the third transitions and the following flat wave segments cut off conducting transistors of the inverter and switch means without overlap.
Claim 3
Dependent Claim
49 words
The combination of claim 1 wherein said means coupled to secondary winding means of said second transformer for driving said control means comprises a pair of windings driving said base electrodes of said pair of rectifier transistor switches with replicas of said periodic waveform that are 180* phase displaced.
Claim 4
Dependent Claim
36 words
The combination of claim 2 wherein the means for driving the control means is connected between the base and collector of the rectifier transistors to supply bias between the base and collector of the rectifier transistors.
Claim 5
Dependent Claim
46 words
The combination of claim 2 wherein the second transformer includes first and second separate winding means, the first winding means being connected between emitter and base electrodes of the inverter transistors, the second winding means being connected between base and collector electrodes of the rectifier transistors.
Claim 6
Dependent Claim
42 words
The combination of claim 3 wherein the first transformer includes power output winding means and the second transformer includes third winding means, means connecting the output winding means and third winding means in series with the rectifier transistor means emitter collector path.
Claim 7
Dependent Claim
41 words
The combination of claim 1 wherein the first transformer includes a power output winding having first and second segments, the emitter collector paths of different rectifier transistors being connected in series between different ones of the winding segments and a load.
Claim 8
Dependent Claim
37 words
The combination of claim 6 wherein the different segments have a common connection with one terminal of the load and similar electrodes of the different rectifier transistors have a common connection with another terminal of the load.
Claim 9
Dependent Claim
43 words
The combination of claim 6 wherein the different segments are split, one end of each split segment being connected to a similar electrode of the different rectifier transistors, the second transformer including winding means connected with the other ends of the split segments.
Claim 10
Dependent Claim
169 words
In combination with a DC to AC inverter including, a pair of transistors driving a first transformer having a core, positive feedback means for coupling said first transformer to a second transformer driving said pair of transistors alternately intO and out of conduction, whereby there is derived in a secondary winding of the second transformer a periodic waveform, means coupling replicas of said waveform to said transistors to drive base electrodes of the transistors in push-pull relationship, an AC to DC rectifier for feeding power from the first transformer to a load, the improvement comprising: a pair of synchronous transistor switch means in said rectifier, each of said transistor switch means having a base electrode and an emitter collector path for feeding power from the first transformer means to the load, and means coupled to secondary winding means of said second transformer for driving said base electrodes with replicas of said periodic waveforms, the replicas driving the base electrodes of the transistor switch means being displaced in phase 180*.
Claim 11
Dependent Claim
169 words
In combination with a DC to AC inverter including, a pair of transistors driving a first transformer having a core, positive feedback means for coupling said first transformer to a second transformer driving said pair of transistors alternately intO and out of conduction, whereby there is derived in a secondary winding of the second transformer a periodic waveform, means coupling replicas of said waveform to said transistors to drive base electrodes of the transistors in push-pull relationship, an AC to DC rectifier for feeding power from the first transformer to a load, the improvement comprising: a pair of synchronous transistor switch means in said rectifier, each of said transistor switch means having a base electrode and an emitter collector path for feeding power from the first transformer means to the load, and means coupled to secondary winding means of said second transformer for driving said base electrodes with replicas of said periodic waveforms, the replicas driving the base electrodes of the transistor switch means being displaced in phase 180*.
Claim 12
Dependent Claim
42 words
The combination of claim 1 wherein the first transformer includes power output winding means and the second transformer includes third winding means, means connecting the output winding means and third winding means in series with the rectifier transistor means emitter collector path.
Claim 13
Dependent Claim
246 words
In combination with a DC to AC inverter including, a pair of transistors driving a first transformer having a core, positive feedback means for coupling said first transformer to a second transformer driving said pair of transistors alternately into and out of conduction, whereby there is derived in a secondary winding of the second transformer a periodic waveform, means coupling replicas of said waveform to said transistors to drive base electrodes of the transistors in push-pull relationship; an AC to DC rectifier for feeding power from the first transformer to a load, the improvement comprising: a pair of synchronous transistor switch means in said rectifier, each of said transistor switch means having a base electrode and an emitter collector path for feeding power from the first transformer means to the load, means for connecting the emitter collector paths with the first transformer means and the load so that the currents in the paths increase with increases in the current supplied by the first transformer to the load, means coupled to secondary winding means of said second transformer for driving said base electrodes with replicas of said periodic waveforms, the replicas driving the base electrodes of the transistor switch means being displaced in phase 180*, said replicas applied to the base electrodes of the transistor switch means being such that the transistors of the switch means are forward biased to a greater extent with increases in the currents supplied through the emitter collector paths to the load.
Claim 14
Dependent Claim
246 words
In combination with a DC to AC inverter including, a pair of transistors driving a first transformer having a core, positive feedback means for coupling said first transformer to a second transformer driving said pair of transistors alternately into and out of conduction, whereby there is derived in a secondary winding of the second transformer a periodic waveform, means coupling replicas of said waveform to said transistors to drive base electrodes of the transistors in push-pull relationship; an AC to DC rectifier for feeding power from the first transformer to a load, the improvement comprising: a pair of synchronous transistor switch means in said rectifier, each of said transistor switch means having a base electrode and an emitter collector path for feeding power from the first transformer means to the load, means for connecting the emitter collector paths with the first transformer means and the load so that the currents in the paths increase with increases in the current supplied by the first transformer to the load, means coupled to secondary winding means of said second transformer for driving said base electrodes with replicas of said periodic waveforms, the replicas driving the base electrodes of the transistor switch means being displaced in phase 180*, said replicas applied to the base electrodes of the transistor switch means being such that the transistors of the switch means are forward biased to a greater extent with increases in the currents supplied through the emitter collector paths to the load.
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) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |