US3770928A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reliable solid state induction cooking appliance with control logic
Assignee: General Electric Co
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Filing: 1971-12-27
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Granted: 1973-11-06
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Expires: 1991-12-27
Abstract
Abstract A smooth-top cooking appliance for inductively heating cooking utensils comprises a flat induction heating coil driven at an ultrasonic frequency by a solid state inverter. The control circuit for the inverter is suitable for fabrication as an integrated circuit and includes, in addition to turn-on circuitry, protection circuits to assure reliable and automatic operation under abnormal circuit conditions such as overvoltages and low input voltages tending to cause device and power circuit failures. The control circuit also includes a utensil presence detection circuit to assure operation under load and no-load conditions. Voltage responsive sensors such as Zener diodes sense the appropriate voltages at selected points on the power circuit and modify the operation of the control circuit, preferably by over-riding and inhibiting the turn-on circuitry. Disclosed with regard to a one-thyristor, variable frequency series resonant inverter with an added maximum frequency control, the protection circuit technique is applicable to inverters generally.
Inventors
- 👤 W Kornrumf
- 👤 J Harnden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:41
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/02; H05B6/06; H05B6/062; H02; H02M; H02M5/00; H02M5/40; H02M5/42; H02M5/44; H02M5/443; H02M5/45; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02M7/505; H02M7/515; H02M7/523; H02M7/525
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
129 words
A reliable solid state cooking appliance for inductively heating a cooking utensil comprising an induction heating coil mounted adjacent a substantially unbroken non-metallic utensil support and producing an alternating magnetic field, a static power conversion circuit including a power circuit controlled by solid state power device means for generating an ultrasonic frequency wave that drives said induction heating coil, and a control circuit operating at signal level and connected to selected points on said power circuit, said control circuit comprising a turn-on circuit for selecting the intervals of conduction of said solid state power device means, and further comprising protection circuit means for detecting predetermined abnormal power circuit conditions and modifying the operation of said control circuit to obtain reliabLe and automatic operation of said static power conversion circuit.
Claim 2
Dependent Claim
129 words
A reliable solid state cooking appliance for inductively heating a cooking utensil comprising an induction heating coil mounted adjacent a substantially unbroken non-metallic utensil support and producing an alternating magnetic field, a static power conversion circuit including a power circuit controlled by solid state power device means for generating an ultrasonic frequency wave that drives said induction heating coil, and a control circuit operating at signal level and connected to selected points on said power circuit, said control circuit comprising a turn-on circuit for selecting the intervals of conduction of said solid state power device means, and further comprising protection circuit means for detecting predetermined abnormal power circuit conditions and modifying the operation of said control circuit to obtain reliabLe and automatic operation of said static power conversion circuit.
Claim 3
Dependent Claim
19 words
A cooking appliance according to claim 1 wherein said protection circuit means modifies the operation of said turn-on circuit.
Claim 4
Dependent Claim
48 words
A cooking appliance according to claim 1 wherein said protection circuit means comprises an overvoltage detection circuit that monitors the voltage at a terminal of said solid state power device means and is operative in response to the sensing of a voltage that rises above a predetermined level.
Claim 5
Dependent Claim
44 words
A cooking appliance according to claim 1 wherein said protection circuit means includes a low input voltage detection circuit that monitors the input voltage to said power circuit and is operative in response to the sensing of a input voltage below a predetermined level.
Claim 6
Dependent Claim
36 words
A cooking appliance according to claim 4 wherein said low input voltage detection circuit is operative during start-up and shut-down of said static power conversion circuit when power is supplied to and removed from said circuit.
Claim 7
Dependent Claim
42 words
A cooking appliance according to claim 1 wherein said turn-on circuit operates at a variable repetition rate to vary the frequency of the ultrasonic wave generated by said static power conversion circuit and thereby adjust the power supplied to the cooking utensil.
Claim 8
Dependent Claim
29 words
A cooking appliance according to claim 6 wherein said protection circuit means also includes a maximum frequency control circuit for limiting the maximum repetition rate of said turn-on circuit.
Claim 9
Dependent Claim
40 words
A cooking appliance according to claim 1 wherein said control circuit further includes a utensil presence detection circuit that senses the absence of a cooking utensil coupled with said induction heating coil and modifies the operation of said control circuit.
Claim 10
Dependent Claim
21 words
A cooking appliance according to claim 8 wherein said utensil presence detection circuit modifies the operation of said turn-on circuit means.
Claim 11
Dependent Claim
138 words
A reliable solid state cooking appliance for inductively heating a cooking utensil comprising an induction heating coil mounted adjacent a substantially unbroken non-metallic utensil support and producing an alternating magnetic field, a static power conversion circuit including a power circuit controlled by solid state power device means for generating an ultrasonic frequency wave that drives said induction heating coil, and a control circuit operating at signal level and including a turn-on circuit for selecting the intervals of conduction of said solid state power device means, and further including utensil presence detection circuit means for sensing a parameter at a selected point on said power circuit during a predetermined time interval and modifying the operation of said control circuit in response to a sensed parameter indicative of the absence of a cooking utensil coupled with said induction heating coil.
Claim 12
Dependent Claim
138 words
A reliable solid state cooking appliance for inductively heating a cooking utensil comprising an induction heating coil mounted adjacent a substantially unbroken non-metallic utensil support and producing an alternating magnetic field, a static power conversion circuit including a power circuit controlled by solid state power device means for generating an ultrasonic frequency wave that drives said induction heating coil, and a control circuit operating at signal level and including a turn-on circuit for selecting the intervals of conduction of said solid state power device means, and further including utensil presence detection circuit means for sensing a parameter at a selected point on said power circuit during a predetermined time interval and modifying the operation of said control circuit in response to a sensed parameter indicative of the absence of a cooking utensil coupled with said induction heating coil.
Claim 13
Dependent Claim
60 words
A cooking appliance according to claim 10 wherein said utensil presence detection circuit means comprises a voltage responsive sensor connected between said selected point on said power circuit and said control circuit, and override circuit means coupled with said voltage responsive sensor for modifying the operation of said turn-on circuit in response to the sensing of a predetermined voltage level.
Claim 14
Dependent Claim
43 words
A cooking appliance according to claim 11 wherein said utensil presence detection circuit means further comprises enabling circuit means responsive to the voltage at said selected point on said power circuit that enables said override circuit means only during said predetermined time interval.
Claim 15
Dependent Claim
18 words
A cooking appliance according to claim 12 wherein said voltage responsive sensor comprises at least one Zener diode.
Claim 16
Dependent Claim
164 words
A reliable solid state cooking appliance for inductively heating a cooking utensil comprising an induction heating coil mounted adjacent a substantially unbroken non-metallic utensil support plate and producing an alternating magnetic field, a static power conversion circuit including a unidirectional input voltage supply and an inVerter power circuit controlled by solid state power device means for generating an ultrasonic frequency wave that drives said induction heating coil, and a signal level control circuit connected to selected points on said power circuit, said control circuit comprising turn-on circuit means for selecting the intervals of conduction of said solid state power device means, protection circuit means for detecting predetermined abnormal power circuit conditions and modifying the operation of said control circuit, and utensil presence detection circuit means for detecting the absence of a cooking utensil on said support coupled with said induction heating coil and for modifying the operation of said control circuit, to thereby achieve reliable and automatic operation of said static power conversion circuit.
Claim 17
Dependent Claim
164 words
A reliable solid state cooking appliance for inductively heating a cooking utensil comprising an induction heating coil mounted adjacent a substantially unbroken non-metallic utensil support plate and producing an alternating magnetic field, a static power conversion circuit including a unidirectional input voltage supply and an inVerter power circuit controlled by solid state power device means for generating an ultrasonic frequency wave that drives said induction heating coil, and a signal level control circuit connected to selected points on said power circuit, said control circuit comprising turn-on circuit means for selecting the intervals of conduction of said solid state power device means, protection circuit means for detecting predetermined abnormal power circuit conditions and modifying the operation of said control circuit, and utensil presence detection circuit means for detecting the absence of a cooking utensil on said support coupled with said induction heating coil and for modifying the operation of said control circuit, to thereby achieve reliable and automatic operation of said static power conversion circuit.
Claim 18
Dependent Claim
37 words
A cooking appliance according to claim 14 wherein said turn-on circuit means has a user adjustable variable repetition rate to vary the frequency of said ultrasonic frequency wave and therefore the power supplied to the cooking utensil.
Claim 19
Dependent Claim
45 words
A cooking appliance according to claim 15 wherein said protection circuit means includes an overvoltage detection circuit that senses a predetermined voltage at a terminal of said solid state power device means and is operative to reduce the repetition rate of said turn-on circuit means.
Claim 20
Dependent Claim
28 words
A cooking appliance according to claim 16 wherein said overvoltage detection circuit comprises a low pass filter so that the circuit is non-responsive to high frequency transient overvoltages.
Claim 21
Dependent Claim
39 words
A cooking appliance according to claim 15 wherein said protection circuit means includes a low input voltage detection circuit that senses a predetermined low input voltage and is operative to reduce the repetition rate of said turn-on circuit means.
Claim 22
Dependent Claim
43 words
A cooking appliance according to claim 18 wherein said low input voltage detection circuit further includes a time delay circuit and an inhibit circuit coupled therewith that reduces the repetition rate of said turn-on circuit means to zero after a predetermined time delay.
Claim 23
Dependent Claim
44 words
A cooking appliance according to claim 15 wherein said utensil presence detection circuit means is operative to reduce the repetition rate of said turn-on circuit in response to the sensing of a power circuit parameter indicative of the absence of a coupled cooking utensil.
Claim 24
Dependent Claim
178 words
A reliable solid state cooking appliance for inductively heating a cooking utensil comprising a nominally flat induction heating coil mounted adjacent a substantially unbroken non-metallic utensil support plate and producing an alternating magnetic field, a static power conversion circuit comprising a unidirectional input voltage supply and a variable ultrasonic output frequency series resonant inverter power circuit controlled by a thyristor device that drives said induction heating coil, and a firing control circuit for said thyristor device energized by low voltage power supply means and including a variable repetition rate firing signal circuit for supplying firing signals to said thyristor device at a selected repetition rate to obtain the desired heating level, said firing control circuit further including protection circuit means comprising overvoltage detection circuit means for sensing the voltage at one terminal of said thyristor device and overriding said firing signal circuit in response to an overvoltage condition, and low input voltage detection circuit means for sensing the input voltage to said inverter circuit and overriding said firing signal circuit in response to a low input voltage condition.
Claim 25
Dependent Claim
178 words
A reliable solid state cooking appliance for inductively heating a cooking utensil comprising a nominally flat induction heating coil mounted adjacent a substantially unbroken non-metallic utensil support plate and producing an alternating magnetic field, a static power conversion circuit comprising a unidirectional input voltage supply and a variable ultrasonic output frequency series resonant inverter power circuit controlled by a thyristor device that drives said induction heating coil, and a firing control circuit for said thyristor device energized by low voltage power supply means and including a variable repetition rate firing signal circuit for supplying firing signals to said thyristor device at a selected repetition rate to obtain the desired heating level, said firing control circuit further including protection circuit means comprising overvoltage detection circuit means for sensing the voltage at one terminal of said thyristor device and overriding said firing signal circuit in response to an overvoltage condition, and low input voltage detection circuit means for sensing the input voltage to said inverter circuit and overriding said firing signal circuit in response to a low input voltage condition.
Claim 26
Dependent Claim
69 words
A cooking appliance according to claim 21 wherein said firing signal circuit comprises a voltage controlled pulse generator whose repetition rate is determined by the voltage on a control capacitor, said control capacitor being connected in series with a user adjustable resistive component between the terminals of said low voltage power supply means to set said control capacitor voltage to obtain the desired inverter output frequency and heating level.
Claim 27
Dependent Claim
33 words
A cooking appliance according to claim 22 wherein said protection circuit means further includes a maximum output frequency control circuit comprising a voltage clamping circuit connected across the terminals of said control capacitor.
Claim 28
Dependent Claim
59 words
A cooking appliance according to claim 22 wherein said overvoltage detection circuit means comprises a voltage responsive sensor connected between a terminal of said thyristor device and said firing control circuit, and a discharge circuit connected across the terminals of said control capacitor and coupled to said voltage responsive sensor to be actuated by the sensing of an overvoltage.
Claim 29
Dependent Claim
18 words
A cooking appliance according to claim 24 wherein said voltage responsive sensor comprises at least one Zener diode.
Claim 30
Dependent Claim
65 words
A cooking appliance according to claim 22 wherein said low input voltage detection circuit means comprises a voltage responsive sensor connected between a terminal of said input voltage source and said firing control circuit, and a voltage clamping circuit connected across the terminals of said control capacitor and coupled to said voltage responsive sensor to be actuated by the sensing of a low input voltage.
Claim 31
Dependent Claim
42 words
A cooking appliance according to claim 26 wherein said low input voltage detection circuit means further comprises inhibit circuit means responsive to the sensing of a low input voltage for inhibiting the production of firing signals by said voltage controlled pulse generator.
Claim 32
Dependent Claim
105 words
A cooking appliance according to claim 22 wherein said firing control circuit further includes a utensil presence detection circuit, said utensil presence detection circuit comprising a voltage responsive sensor connected between a terminal of said thyristor device and said firing control circuit, a discharge circuit connected across the terminals of said control capacitor and coupled with said voltage responsive sensor to be actuated by the sensing of a predetermined voltage, and discharge circuit enabling means having a connection to a terminal of said thyristor device for enabling said discharge circuit only during a predetermined time interval following reapplication of forward voltage to said thyristor device.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-05 | 1977-05-07 | 1977-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-05 | 1981-05-07 | 1981-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-05 | 1985-05-07 | 1985-11-06 | $7700.00 | Window Closed / Lapsed |