US3820005A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inverter with constant duty cycle control
Assignee: General Electric Co
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Filing: 1973-03-09
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Granted: 1974-06-25
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Expires: 1993-03-09
Abstract
Abstract An inverter for driving an induction heating coil utilizes a constant duty cycle control circuit to optimize performance with the load coupled with and removed from the energized coil. To compensate for the increased period of oscillation when unloaded, the inverter operating frequency is automatically decreased to reduce voltage and current stresses on circuit components. An onoff sensor continuously senses an inverter circuit parameter indicative of the load condition, such as a voltage divider and associated switch for sensing the thyristor anode voltage. The sensed information is processed by the control circuit in closed feedback loop manner to vary the thyristor gating signal repetition rate.
Inventors
- 👤 R Steigerwald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:12
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/02; H05B6/06; H05B6/062; G; G05; G05F; G05F1/00; G05F1/10; G05F1/12; G05F1/40; G05F1/44; H02; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/523
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
148 words
A solid state power conversion circuit for optimum performance under different load conditions comprising a variable operating frequency inverter power circuit controlled by solid state power device means, a signal level constant duty cycle control circuit for supplying gating signals to said solid state power device means to continuously vary the inverter operating frequency in accordance with the load condition of said inverter, said constant duty cycle control circuit being controlled by an on-off sensor connected between said inverter power circuit and said control circuit for sensing a preselected power circuit parameter indicative of the load condition of said inverter, in which said on-off sensor is comprised by a resistance voltage divider circuit connected between a pair of selected points on said inverter power circuit, and further includes a switching device coupled to a junction of said voltage divider to produce a train of variable width voltage pulses.
Claim 2
Dependent Claim
148 words
A solid state power conversion circuit for optimum performance under different load conditions comprising a variable operating frequency inverter power circuit controlled by solid state power device means, a signal level constant duty cycle control circuit for supplying gating signals to said solid state power device means to continuously vary the inverter operating frequency in accordance with the load condition of said inverter, said constant duty cycle control circuit being controlled by an on-off sensor connected between said inverter power circuit and said control circuit for sensing a preselected power circuit parameter indicative of the load condition of said inverter, in which said on-off sensor is comprised by a resistance voltage divider circuit connected between a pair of selected points on said inverter power circuit, and further includes a switching device coupled to a junction of said voltage divider to produce a train of variable width voltage pulses.
Claim 3
Dependent Claim
58 words
A circuit according to claim 1 wherein said constant duty cycle control circuit further includes an averaging filter circuit for converting said train of pulses to a variable direct voltage signal, and a voltage controlled oscillator and pulse generator for generating said gating signals at a variable repetition rate dependent on the magnitude of said direct voltage signal.
Claim 4
Dependent Claim
203 words
A solid state power conversion circuit for optimum performance under different load conditions comprising a variable operating frequency inverter power circuit controlled by solid state power device means, a signal level constant duty cycle control circuit for supplying gating signals to said solid state power device means to continuously vary the inverter operating frequency in accordance with the load condition of said inverter, said constant duty cycle control circuit being controlled by an on-off sensor connected between said inverter power circuit and said control circuit for sensing a preselected power circuit parameter indicative of the load condition of said inverter, in which said inverter power circuit is a one-thyristor series resonant circuit and said solid state power device means is comprised by the inverse-parallel combination of a thyristor and a diode, said on-off sensor comprises a voltage divider circuit effectively connected across the terminals of said thyristor to sense the thyristor anode voltage, and further comprises a switching device connected to a junction of said voltage divider circuit for generating a train of variable width voltage pulses, and said constant duty cycLe control circuit includes means controlled by said variable width voltage pulses for producing said gating signals at a variable repetition rate.
Claim 5
Dependent Claim
203 words
A solid state power conversion circuit for optimum performance under different load conditions comprising a variable operating frequency inverter power circuit controlled by solid state power device means, a signal level constant duty cycle control circuit for supplying gating signals to said solid state power device means to continuously vary the inverter operating frequency in accordance with the load condition of said inverter, said constant duty cycle control circuit being controlled by an on-off sensor connected between said inverter power circuit and said control circuit for sensing a preselected power circuit parameter indicative of the load condition of said inverter, in which said inverter power circuit is a one-thyristor series resonant circuit and said solid state power device means is comprised by the inverse-parallel combination of a thyristor and a diode, said on-off sensor comprises a voltage divider circuit effectively connected across the terminals of said thyristor to sense the thyristor anode voltage, and further comprises a switching device connected to a junction of said voltage divider circuit for generating a train of variable width voltage pulses, and said constant duty cycLe control circuit includes means controlled by said variable width voltage pulses for producing said gating signals at a variable repetition rate.
Claim 6
Dependent Claim
164 words
A solid state power conversion circuit for optimum performance under different load conditions comprising a variable operating frequency series resonant inverter power circuit which includes solid state power device means having a variable conduction interval that depends on the inverter load condition, a signal level constant duty cycle control circuit for supplying gating signals to said solid state power device means to continuously vary the inverter operating frequency in accordance with the inverter load condition, an on-off sensor including a resistance voltage divider circuit comprised by a plurality of series connected resistors that are effectively connected directly across a pair of power circuit terminals of said solid state power device means to sense alternating intervals of conduction and nonconduction thereof, said constant duty cycle control circuit being coupled to one of said voltage divider resistors and controlled by the alternating intervals of voltage and substantially no voltage thereacross corresponding respectively to the intervals of nonconduction and conduction of said solid state power device means.
Claim 7
Dependent Claim
164 words
A solid state power conversion circuit for optimum performance under different load conditions comprising a variable operating frequency series resonant inverter power circuit which includes solid state power device means having a variable conduction interval that depends on the inverter load condition, a signal level constant duty cycle control circuit for supplying gating signals to said solid state power device means to continuously vary the inverter operating frequency in accordance with the inverter load condition, an on-off sensor including a resistance voltage divider circuit comprised by a plurality of series connected resistors that are effectively connected directly across a pair of power circuit terminals of said solid state power device means to sense alternating intervals of conduction and nonconduction thereof, said constant duty cycle control circuit being coupled to one of said voltage divider resistors and controlled by the alternating intervals of voltage and substantially no voltage thereacross corresponding respectively to the intervals of nonconduction and conduction of said solid state power device means.
Claim 8
Dependent Claim
49 words
A circuit according to claim 4 wherein said on-off sensor further includes a switching device operatively connected to said one voltage divider resistor and controlled by the voltage thereacross to produce a train of variable width voltage pulses that are supplied to said signal level constant duty control circuit.
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) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |