US3792337A
Expired / Lapsed
US
⏱️ 0.0 years remaining
D. c. to d. c. converter
Assignee: Allis Chalmers Corp
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Filing: 1973-02-20
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Granted: 1974-02-12
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Expires: 1993-02-20
Abstract
Abstract A D.C. to D.C. converter has a transformer with a magnetic core which is not of square loop material, a control transistor between the midtap of the transformer feedback winding and the grounded emitters of the first and second switching transistors for completing base drive circuits thereto, a current limit emitter resistor for each switching transistor, and a diode for coupling the voltage developed across the emitter resistor to the base of the control transistor. When the converter is oscillating and the core approaches saturation, a spike of current is generated which flows through the emitter resistor of the conducting switching transistor and develops a voltage which biases the control transistor off to thereby remove base drive to the switching transistors. The resulting decay in flux in the core reverses the polarity of base drive to the switching transistors. In a preferred embodiment for generating an SCR firing signal, a full wave rectifier is connected to the transformer output winding, a voltage divider is connected across the rectifier output, the voltage developed across a first portion of the voltage divider may be coupled to the SCR gating circuit, and the series arrangement of a capacitor and resistor is connected across the remainder of the voltage divider. The capacitor is initially discharged and forms a low impedance shunt to said remainder of the voltage divider so that the SCR firing signal developed across the first portion thereof has a steep leading edge and decays in magnitude with time to a constant value as the capacitor changes, whereby the average power rating of the SCR gating circuit is not exceeded.
Inventors
- 👤 T Gilmore
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:24
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/08; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/338; H02M3/3382; H02M3/3384
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
166 words
In an oscillating circuit D.C. to D.C. converter wherein first and second switching transistors are regeneratively swtiched into conduction alternately by feedback signals from a transformer provided with a midtapped primary winding having its ends coupled to the respective transistor collectors and a midtapped feedback winding inductively linked to said primary winding through said transformer magnetic core and having its ends coupled to the respective transistor bases, the improvement comprising control transistor means between the midtap of said feedback winding and the emitters of each said switching transistor for completing base drive circuits to said switching transistors, said transformer having a core which is not of square loop material, and current limit means associated with each said switching transistor for biasing said control transistor means off when the magnetic flux in said core approaches saturation, whereby the decay of flux in said core when said control transistor means turns off to open said base drive circuits reverses the polarity of base drives to said switching transistors.
Claim 2
Dependent Claim
166 words
In an oscillating circuit D.C. to D.C. converter wherein first and second switching transistors are regeneratively swtiched into conduction alternately by feedback signals from a transformer provided with a midtapped primary winding having its ends coupled to the respective transistor collectors and a midtapped feedback winding inductively linked to said primary winding through said transformer magnetic core and having its ends coupled to the respective transistor bases, the improvement comprising control transistor means between the midtap of said feedback winding and the emitters of each said switching transistor for completing base drive circuits to said switching transistors, said transformer having a core which is not of square loop material, and current limit means associated with each said switching transistor for biasing said control transistor means off when the magnetic flux in said core approaches saturation, whereby the decay of flux in said core when said control transistor means turns off to open said base drive circuits reverses the polarity of base drives to said switching transistors.
Claim 3
Dependent Claim
57 words
In a D.C. to D.C. converter in accordance with claim 1 and including selectively controllable converter starting transistor means for coupling a unidirectional voltage to said feedback winding to thereby turn on one of said switching transistors, means responsive to the flow of current in said one switching transistor for biasing said control transistor means into conduction.
Claim 4
Dependent Claim
24 words
In a D.C. to D.C. converter in accordance with claim 1 and including means to selectively turn said control transistor means on and off.
Claim 5
Dependent Claim
48 words
In a D.C. to D.C. converter in accordance with claim 1 wherein each said current limit means includes an emitter resistor for the associated switching transistor, and means including a diode for coupling the voltage developed across said emitter resistor to the base of said control transistor means.
Claim 6
Dependent Claim
51 words
In a D.C. to D.C. converter in accordance with claim 4 and including a unidirectional voltage source connected to the midtap of said primary windinG and wherein one end of each emitter resistor and an electrode of said control transistor means is coupled to one side of said unidirectional voltage source.
Claim 7
Dependent Claim
69 words
In a D.C. to D.C. converter in accordance with claim 5 wherein said one end of said emitter resistor, said one electrode of said control transistor means, and said one side of said voltage source are grounded, and the decrease in incremental permeability when said core approaches saturation results in a spike of emitter current in the conducting switching transistor which effects turning off of said control transistor means.
Claim 8
Dependent Claim
102 words
In a D.C. to D.C. converter in accordance with claim 1 for generating an SCR firing signal wherein said transformer has an output winding inductively linked to said transformer core, full wave rectifier means connected to said output winding, first and second resistors connected in series across the output of said full wave rectifier means, and the series arrangement of a third resistor and a capacitor being connected in shunt to said first resistor, whereby an SCR firing signal is developed across said second resistor which has a steep leading edge and decays in magnitude with time to a reduced constant value.
Claim 9
Dependent Claim
175 words
A D.C. to D.C. converter comprising, in combination, first and second switching transistors, a transformer having a magnetic core which is not of square loop material and midtapped primary, feedback, and output windings inductively linked with said core, the ends of said primary winding being respectively coupled to the collectors of said first and second transitors and the ends of said feedback winding being respectively coupled to the bases of said first and second transistors, a D.C. voltage source coupled to the midtap of said primary winding, control transistor means between the midtap of said feedback winding and the emitter of each switching transistor for completing base drive circuits to said switching transistors, and means associated with each switching transistor and including an emitter resistor for biasing said control transistor means off when the associated switch transistor approaches saturation, whereby the decay of flux in said core when said control transistor means turns off to open said base drive circuit reverses the polarity of base drive to said switching transistors so that they conduct alternately.
Claim 10
Dependent Claim
175 words
A D.C. to D.C. converter comprising, in combination, first and second switching transistors, a transformer having a magnetic core which is not of square loop material and midtapped primary, feedback, and output windings inductively linked with said core, the ends of said primary winding being respectively coupled to the collectors of said first and second transitors and the ends of said feedback winding being respectively coupled to the bases of said first and second transistors, a D.C. voltage source coupled to the midtap of said primary winding, control transistor means between the midtap of said feedback winding and the emitter of each switching transistor for completing base drive circuits to said switching transistors, and means associated with each switching transistor and including an emitter resistor for biasing said control transistor means off when the associated switch transistor approaches saturation, whereby the decay of flux in said core when said control transistor means turns off to open said base drive circuit reverses the polarity of base drive to said switching transistors so that they conduct alternately.
Claim 11
Dependent Claim
62 words
A D.C. to D.C. converter in accordance with claim 8 wherein one end of each said emitter resistors is coupled to one side of said voltage source, and said means for biasing said control transistor means off is actuated when said core approaches saturation and the decreases in its incremental permeability results in an emitter current spike in the conducting switching transistor.
Claim 12
Dependent Claim
64 words
A D.C. to D.C. converter in accordance with claim 8 wherein one end of each emitter resistor, one electrode of said control transistor means, and one side of said voltage source are grounded, and each said means for biasing said control transistor means off includes a diode coupling the voltage developed across the associated emitter resistor to the base of said control transistor means.
Claim 13
Dependent Claim
85 words
A D.C. to D.C. converter in accordance with claim 8 for generating an SCR firing signal and including, full wave rectifier means coupled to said output winding, a voltage divider connected across the output of said rectifier means, and a resistor and a capacitor connected in series across a portion of said voltage divider, whereby the voltage developed across the remainder of said voltage divider constituting said SCR firing signal has a steep leading edge and decays in magnitude with time to a constant value.
Claim 14
Dependent Claim
58 words
A D.C. to D.C. converter in accordance with claim 8 and including selectively controllable converter starting transistor means for coupling a unidirectional voltage to said feedback winding to thereby turn on one of said switching transistors, and, means responsive to the resultIng flow of current in said one switching transistor for biasing said control transistor means into conduction.
Claim 15
Dependent Claim
66 words
A D.C. to D.C. converter in accordance with claim 12 wherein the emitter-collector circuit of said control transistor means is coupled between the midtap of said feedback winding and one end of each said emitter resistor, and each said means for biasing said control transistor means off includes a diode between the emitter of the associated switching transistor and the base of said control transistor means.
Claim 16
Dependent Claim
96 words
A D.C. to D.C. converter in accordance with claim 13 wherein said converter starting means includes an oscillation starting transistor having its emitter connected to said midtap of said feedback winding and its collector connected through a biasing resistor to the base of said control transistor means, a unidirectional voltage source, and transistor means selectively controllable to on and off conditions by logic voltage input signals thereto for coupling said unidirectional voltage source to the base of said oscillation starting transistor, and wherein said means for biasing said control transistor into conduction includes said biasing resistor.
Claim 17
Dependent Claim
23 words
A D.C. to D.C. converter in accordance with claim 7 and including means to selectively bias said control transistor means on and off.
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) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |