US3667016A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Regenerative braking circuit for induction motors
Assignee: Honeywell Inc
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Filing: 1971-05-03
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Granted: 1972-05-30
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Expires: 1991-05-03
Abstract
Abstract An induction motor is normally driven from a clock source acting through a power bridge inverter. Braking is accomplished by substituting a feedback signal for the clock signal. A tachometer in the feedback loop monitors the actual motor speed and cooperates to produce a feedback signal having a frequency characteristic that represents a predetermined fraction of the actual motor speed. When the feedback signal is applied to the motor through the power bridge inverter, the excitation frequency becomes and remains less than the frequency necessary to maintain the prevailing motor speed so that the motor operates in a negative slip mode in which it is quickly brought to a smooth stop.
Inventors
- 👤 John C G Dunfield
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:32
CPC Classifications
H; H02; H02P; H02P3/00; H02P3/06; H02P3/18
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
98 words
A braking circuit for use with an induction motor of the type normally energized in response to signals from a constant frequency clock source, said signals having a pulse repetition rate corresponding to the normal running speed of the motor, said braking circuit comprising means to monitor the speed of said motor, means responsive to said monitoring means for providing a feedback signal having a pulse repetition rate corresponding to a motor speed less than that sensed by said monitoring means, and switching means for optionally energizing said motor from said clock source or from said feedback signal.
Claim 2
Dependent Claim
98 words
A braking circuit for use with an induction motor of the type normally energized in response to signals from a constant frequency clock source, said signals having a pulse repetition rate corresponding to the normal running speed of the motor, said braking circuit comprising means to monitor the speed of said motor, means responsive to said monitoring means for providing a feedback signal having a pulse repetition rate corresponding to a motor speed less than that sensed by said monitoring means, and switching means for optionally energizing said motor from said clock source or from said feedback signal.
Claim 3
Dependent Claim
36 words
The apparatus of claim 1 further including a power bridge inverter interconnecting said switching means and said motor, said inverter being constructed to convert signals from said switching means into signals suitable for driving said motor.
Claim 4
Dependent Claim
58 words
The apparatus of claim 2 in which said switching means is connected to respond to an externally applied brake command signal, said switching means being constructed to pass a signal only from said clock means in the absence of a brake command signal and to pass only a feedback signal in the presence of a brake command signal.
Claim 5
Dependent Claim
28 words
The apparatus of claim 3 in which said monitoring means includes a digital tachometer for producing a specified number of pulses for each revolution of the motor shaft.
Claim 6
Dependent Claim
26 words
The apparatus of claim 4 further iNcluding a buffer means for converting the pulses from said tachometer into pulses suitable for driving said power bridge inverter.
Claim 7
Dependent Claim
63 words
The apparatus of claim 4 further including a voltage controlled oscillator and a demodulating means, said demodulating means being constructed to provide a DC signal having a magnitude indicative of the pulse repetition rate of a signal from said tachometer, said oscillator being constructed and arranged to provide a signal to said switching means that varies with the magnitude of said DC signal.
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) | 1975-05-30 | 1975-11-29 | 1976-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-30 | 1979-11-29 | 1980-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-30 | 1983-11-29 | 1984-05-30 | $7700.00 | Window Closed / Lapsed |