Patent US3767988A successfully refreshed from Google Patents.
US3767988A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Motor control circuit and three-phase generator with stationary components
Assignee: Danfoss AS
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Filing: 1970-12-03
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Granted: 1973-10-23
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Expires: 1990-12-03
Abstract
Abstract An electrical three-phase generator and motor control circuit. The generator is made of three alike wave-generating units in cascade each generating a respective trapezoidal wave corresponding to a respective phase of the generator. Each unit comprises a small detector in series with a control circuit varying the amplitude of the wave proportionately to a control voltage representative of and corresponding to variations of voltage from voltage sources and applied to a motor and an integrating circuit consisting of an integrating amplifier and an integrating capacitor and a double limiter in parallel therewith. The control voltage is developed by a voltage divider across the motor control circuit.
Inventors
- 👤 A Jensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:19
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02M; H02M7/00; H02M7/42; H02M7/44; H02M7/48; H02P2201/00; H02P2201/03; H02P27/047
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
152 words
In combination in a motor control circuit for an induction motor, an induction motor, voltage sources energizing said motor, means developing a control voltage varying proportionately to variations of the voltage from said sources applied to said motor, means comprising a three-phase generator under control of said control signal generating three waves each comprising positive and negative half-waves each having a trapezoidal waveform, and means applying the half-waves to said motor to control its torque and maintain it substantially constant regardless of variation of the voltage from said sources, said three-phase generator including (1) three wave-generating units in cascade with each unit including a null detector, (2) a control circuit receptive of said control signal and in series with said null detector, and (3) an integrating circuit receptive of the output of said control circuit, said trapezoidal waveform comprising three sections with each said section having a duration of 60 electrical degrees.
Claim 2
Dependent Claim
152 words
In combination in a motor control circuit for an induction motor, an induction motor, voltage sources energizing said motor, means developing a control voltage varying proportionately to variations of the voltage from said sources applied to said motor, means comprising a three-phase generator under control of said control signal generating three waves each comprising positive and negative half-waves each having a trapezoidal waveform, and means applying the half-waves to said motor to control its torque and maintain it substantially constant regardless of variation of the voltage from said sources, said three-phase generator including (1) three wave-generating units in cascade with each unit including a null detector, (2) a control circuit receptive of said control signal and in series with said null detector, and (3) an integrating circuit receptive of the output of said control circuit, said trapezoidal waveform comprising three sections with each said section having a duration of 60 electrical degrees.
Claim 3
Dependent Claim
35 words
The combination according to claim 1, in which said integrating circuit comprises an integrating amplifier, an integrating capacitor in parallel with said amplifier, and a double limiter across said amplifier in parallel with said capacitor.
Claim 4
Dependent Claim
19 words
The combination according to claim 2, in which said double limiter comprises two zener diodes connected back to back.
Claim 5
Dependent Claim
75 words
The combination according to claim 1 in which said null detector comprises two series transistors, one of said transistors having an output collector, said amplifier comprising an input transistor having a base and an output transistor, two resistors connecting said output collector to said base of said input transistor, two parallel diodes connected in opposite polarity at junctions between said resistors, said double limiter comprising two zener diodes connected back to back across said amplifier.
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) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |