US3737756A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Converter circuit with balanced parallel switching paths
Assignee: AT&T Inc
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Filing: 1972-05-15
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Granted: 1973-06-05
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Expires: 1992-05-15
Abstract
Abstract A single ended converter includes a differential transformer arrangement to constrain paralleled switching transistors to operate with equal current loads. The differential transformer has magnetically coupled windings in the output and the base drive circuits in each of the switching transistors. If the switching transistors conduct unequal currents, flux is produced in the differential transformer which generates base drive signals to restore equal current loads in the paralleled switching transistors. The output voltage is regulated by a feedback circuit which controls the switching of the paralleled switching devices. The feedback circuit operates in a pseudorandom fashion and hence switches the transistors at varying frequencies and varying duty cycles. This advantageously reduces the acoustic noise of the converter.
Inventors
- 👤 A Hasley
- 👤 R Hock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:41
CPC Classifications
H; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/53; H02M7/537; H02M7/538; H02M7/5381; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/337; H02M3/3376; H02M3/3378
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
176 words
A DC to DC converter comprising input terminals, a converter power transformer and output terminals, first and second switching devices connected in parallel and coupling said input terminals to said converter power transformer, means to switch said switching devices and means to balance the respective current loads flowing in said switching devices, said means to balance comprising a differential transformer including first and second windings in the main conduction paths of said first and second switching devices, respectively, and third and fourth windings coupling said means to switch to said first and second switching devices, respectively, said first, second, third and fOurth windings being magnetically coupled to each other by being wound on a common flux path device, said first and second windings oriented to generate opposing fluxes, said third and fourth windings oriented to generate opposing fluxes and said first and third and second and fourth windings oriented to generate summing fluxes, respectively, whereby the induced voltages due to flux in said common flux path constrain the switching devices to operate with equal current loads.
Claim 2
Dependent Claim
176 words
A DC to DC converter comprising input terminals, a converter power transformer and output terminals, first and second switching devices connected in parallel and coupling said input terminals to said converter power transformer, means to switch said switching devices and means to balance the respective current loads flowing in said switching devices, said means to balance comprising a differential transformer including first and second windings in the main conduction paths of said first and second switching devices, respectively, and third and fourth windings coupling said means to switch to said first and second switching devices, respectively, said first, second, third and fOurth windings being magnetically coupled to each other by being wound on a common flux path device, said first and second windings oriented to generate opposing fluxes, said third and fourth windings oriented to generate opposing fluxes and said first and third and second and fourth windings oriented to generate summing fluxes, respectively, whereby the induced voltages due to flux in said common flux path constrain the switching devices to operate with equal current loads.
Claim 3
Dependent Claim
65 words
A DC to DC converter as defined in claim 1 wherein said means to switch comprises a periodic pulse source and means to apply pulses of said periodic pulse source to said switching devices, feedback means to regulate the voltage across the output terminals of said converter and means responsive to said feedback means to inhibit the transmission of signals through said means to apply.
Claim 4
Dependent Claim
73 words
A DC to DC converter as defined in claim 2 wherein said converter power transformer includes a primary winding, a secondary winding and a tertiary winding, a rectifier diode to connect said secondary winding to said output terminals, a second diode coupling said tertiary winding to said means to inhibit and poled to conduct when said rectifier diode is conducting in order to inhibit said switching devices when said rectifier diode is conducting.
Claim 5
Dependent Claim
97 words
A DC to DC converter as defined in claim 3 wherein said feedback means comprises means to compare the voltage at said output terminal with a reference voltage, means to generate an error signal therefrom, means to generate an optical signal in response to said error signal, optically responsive means to generate a voltage, bistable means to compare the voltage generated by said optically responsive means with a second voltage and means to utilize the output of said bistable means to compare to activate said means to inhibit the transmission of signals through said means to apply.
Claim 6
Dependent Claim
132 words
A power supply circuit including at least two paralleled switching transistors switching in phase with each other, a current balance control circuit to equalize current loads in at least two of said paralleled switching transistors comprising a first and a second switching transistors, a magnetic medium, a first and a second winding connected in series with the main conduction path of said first and second switching transistors respectively, a third and fourth winding connected to the control electrodes of said first and second switching transistors, respectively, said first, second, third and fourth windings oriented on said magnetic medium so that a current difference in said first and second windings induces signals in said third and fourth windings which alter the conductivity of said first and second switching transistors to eliminate said differences.
Claim 7
Dependent Claim
132 words
A power supply circuit including at least two paralleled switching transistors switching in phase with each other, a current balance control circuit to equalize current loads in at least two of said paralleled switching transistors comprising a first and a second switching transistors, a magnetic medium, a first and a second winding connected in series with the main conduction path of said first and second switching transistors respectively, a third and fourth winding connected to the control electrodes of said first and second switching transistors, respectively, said first, second, third and fourth windings oriented on said magnetic medium so that a current difference in said first and second windings induces signals in said third and fourth windings which alter the conductivity of said first and second switching transistors to eliminate said differences.
Claim 8
Dependent Claim
50 words
A circuit as defined in claim 5 further including a converter power transformer, signal regulation circuitry and a periodic pulse source connected to drive said paralleled switching transistors, means responsive to said signal regulation circuitry to disrupt the connection of said periodic pulse source to drive said paralleled switching transistor.
Claim 9
Dependent Claim
45 words
A circuit as defined in claim 6 further including output terminals and a rectifying diode to connect said transformer to said output terminals, said transformer including a tertiary winding and means responsive to the signal on said tertiary winding to activate said means to disrupt.
Claim 10
Dependent Claim
144 words
A circuit as defined in claim 5 further including third and fourth switching transistors respectively, a second magnetic medium, said fifth, sixth, seventh and eighth windings oriented on said second magnetic medium so that a current difference in said fifth and sixth windings induces signals in said seventh and eighth windings which alter the conductivity of said third and fourth switching transistors to eliminate said differences in said fifth and sixth windings and third means to balance the current load in said first and second transistors with the current load in said third and fourth tRansistors including a third magnetic medium, ninth and tenth windings to sense the current load in said first and second transistors and said third and fourth transistors and bias windings coupled to each of said transistors, said ninth, tenth and bias windings being wound on said third magnetic medium.
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) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |