US3700988A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Speed control system for alternating current induction motors
Assignee: Individual
•
Filing: 1971-05-27
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Granted: 1972-10-24
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Expires: 1991-05-27
Abstract
Abstract A speed control system for alternating current induction motors wherein a reference potential, which is a rectified phase of the alternating current supply potential, is connected across the series combination of a variable resistor and the timing capacitor of a unijunction transistor type relaxation oscillator circuit and a direct current control potential, which is a function of motor speed and which may be selectively varied in magnitude to change the speed of the motor, is connected across the variable resistor in the same polarity relationship as the reference potential. The unijunction transistor type relaxation oscillator circuit and associated circuitry produces a trigger signal at the electrical angle of each potential cycle of each phase of the alternating current supply potential as determined by the difference of magnitude between the reference and control potentials which trigger respective silicon controlled rectifiers conductive to complete an energizing circuit for the corresponding phase winding or the motor. Another capacitor, connected across the series combination of the variable resistor and the timing capacitor, establishes the difference of magnitude between the reference and control potentials at substantially zero upon motor start and increases the difference at a predetermined rate to a maximum as determined by the selected magnitude of the control potential.
Inventors
- 👤 Bohdan I Pryjmak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 01:08
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/02; H02P27/026; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/292; H02P7/293
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
212 words
A speed control system for alternating current motors of the type having discrete phase windings corresponding to each phase of a compatible alternating current supply potential comprising, means for producing a reference potential in synchronism with a selected phase of said alternating current supply potential, means for producing a control potential which varies in magnitude with changes of motor speed, means for selectively varying the magnitude of said control potential for varying the speed of said motor, means including a unijunction traNsistor type relaxation oscillator circuit having a timing capacitor responsive to a difference in magnitude between said reference potential and said control potential for producing a trigger signal at the electrical angle of each potential cycle of each phase of said alternating current supply potential as determined by the magnitude of said difference, means for establishing said difference of magnitude between said reference potential and said control potential at substantially zero upon motor start and for increasing said difference in magnitude at a predetermined rate to a maximum as determined by the selected magnitude of said control potential, and controllable switching circuit means corresponding to each phase of said alternating current supply potential for completing an energizing circuit for the corresponding said phase windings in response to respective said trigger signals.
Claim 2
Dependent Claim
212 words
A speed control system for alternating current motors of the type having discrete phase windings corresponding to each phase of a compatible alternating current supply potential comprising, means for producing a reference potential in synchronism with a selected phase of said alternating current supply potential, means for producing a control potential which varies in magnitude with changes of motor speed, means for selectively varying the magnitude of said control potential for varying the speed of said motor, means including a unijunction traNsistor type relaxation oscillator circuit having a timing capacitor responsive to a difference in magnitude between said reference potential and said control potential for producing a trigger signal at the electrical angle of each potential cycle of each phase of said alternating current supply potential as determined by the magnitude of said difference, means for establishing said difference of magnitude between said reference potential and said control potential at substantially zero upon motor start and for increasing said difference in magnitude at a predetermined rate to a maximum as determined by the selected magnitude of said control potential, and controllable switching circuit means corresponding to each phase of said alternating current supply potential for completing an energizing circuit for the corresponding said phase windings in response to respective said trigger signals.
Claim 3
Dependent Claim
208 words
A speed control system for alternating current motors of the type having discrete phase windings corresponding to each phase of a compatible alternating current supply potential comprising, means for producing a reference potential in synchronism with a selected phase of said alternating current supply potential, means for producing a control potential which varies in magnitude with changes of motor speed, means for selectively varying the magnitude of said control potential for varying the speed of said motor, means including a unijunction transistor type relaxation oscillator circuit having a timing capacitor charged by a charging potential of a magnitude determined by the difference in magnitude between said reference potential and said control potential for producing a trigger signal at the electrical angle of each potential cycle of each phase of said alternating current supply potential as determined by the magnitude of said difference, means for increasing the magnitude of said capacitor charging potential at a predetermined rate from substantially zero upon motor start to a maximum as determined by the selected magnitude of said control potential, and controllable switching circuit means corresponding to each phase of said alternating current supply potential for completing an energizing circuit for the corresponding said phase windings in response to respective said trigger signals.
Claim 4
Dependent Claim
208 words
A speed control system for alternating current motors of the type having discrete phase windings corresponding to each phase of a compatible alternating current supply potential comprising, means for producing a reference potential in synchronism with a selected phase of said alternating current supply potential, means for producing a control potential which varies in magnitude with changes of motor speed, means for selectively varying the magnitude of said control potential for varying the speed of said motor, means including a unijunction transistor type relaxation oscillator circuit having a timing capacitor charged by a charging potential of a magnitude determined by the difference in magnitude between said reference potential and said control potential for producing a trigger signal at the electrical angle of each potential cycle of each phase of said alternating current supply potential as determined by the magnitude of said difference, means for increasing the magnitude of said capacitor charging potential at a predetermined rate from substantially zero upon motor start to a maximum as determined by the selected magnitude of said control potential, and controllable switching circuit means corresponding to each phase of said alternating current supply potential for completing an energizing circuit for the corresponding said phase windings in response to respective said trigger signals.
Claim 5
Dependent Claim
226 words
A speed control system for alternating current motors of the type having discrete phase windings corresponding to each phase of a compatible alternating current supply potential comprising, means for producing a reference potential in synchronism with a selected phase of said alternating current supply potential, means for producing a control potential which varies in magnitude with changes of motor speed, means for selectively varying the magnitude of said control potential for varying the speed of said motor, means including a unijunction transistor type relaxation oscillator circuit having a timing capacitor responsive to a difference in magnitude between said reference potential and said control potential for producing a trigger signal at the electrical angle of each potential cycle of each phase of said alternating current supply potential as determined by the magnitude of said difference, an impedance element, means for connecting said reference potential across the series combination of said impedance element and said timing capacitor, means for connecting said control potential across said impedance element in the same polarity relationship as said reference potential, a capacitor, means for connecting said capacitor across said series combination of said impedance element and said timing capacitor, and controllable switching circuit means corresponding to each phase of said alternating current supply potential for completing an energizing circuit for the corresponding said phase windings in response to respective said trigger signals.
Claim 6
Dependent Claim
226 words
A speed control system for alternating current motors of the type having discrete phase windings corresponding to each phase of a compatible alternating current supply potential comprising, means for producing a reference potential in synchronism with a selected phase of said alternating current supply potential, means for producing a control potential which varies in magnitude with changes of motor speed, means for selectively varying the magnitude of said control potential for varying the speed of said motor, means including a unijunction transistor type relaxation oscillator circuit having a timing capacitor responsive to a difference in magnitude between said reference potential and said control potential for producing a trigger signal at the electrical angle of each potential cycle of each phase of said alternating current supply potential as determined by the magnitude of said difference, an impedance element, means for connecting said reference potential across the series combination of said impedance element and said timing capacitor, means for connecting said control potential across said impedance element in the same polarity relationship as said reference potential, a capacitor, means for connecting said capacitor across said series combination of said impedance element and said timing capacitor, and controllable switching circuit means corresponding to each phase of said alternating current supply potential for completing an energizing circuit for the corresponding said phase windings in response to respective said trigger signals.
References Cited (Backward Citations)
US3602787A
Cited
US3614596A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |