US3906315A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Closed-loop, precision-stop induction motor control circuit
Assignee: Aerojet Rocketdyne Inc
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Filing: 1974-01-15
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Granted: 1975-09-16
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Expires: 1994-01-15
Abstract
Abstract An induction motor deceleration control circuit capable of activating apparatus peripheral to the induction motor when the motor output shaft is at a predetermined speed and position, and then stopping the output shaft precisely at a predetermined position, all in a rapid one-step operation, is illustrated herein. The control circuit includes apparatus for providing an AC drive signal to the induction motor, a control for reducing the frequency of that AC drive signal in order to reduce the operating speed of the motor, a feedback loop for identifying the speed and position of the motor output shaft, and a brake control responsive to the feedback loop for converting the AC drive signal to a DC braking signal when the motor shaft slows to a predetermined speed and reaches a predetermined position. The controlled application of a braking signal in accordance with motor output shaft speed and position ensures that the shaft will only rotate through a known angle after application of the braking force and thus stop precisely at a predetermined distance. The control circuit also includes apparatus responsive to the feedback circuit for activating apparatus peripheral to the induction motor just before the induction motor is stopped, when the motor output shaft has a predetermined speed and position.
Inventors
- 👤 Theodore H Gotisar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:11
CPC Classifications
H; H02; H02P; H02P3/00; H02P3/06; H02P3/18; G; G05; G05D; G05D3/00; G05D3/12; G05D3/20
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
164 words
A precision-stop control circuit for controlling an electric induction motor having a movable output member, said circuit comprising: means for providing a cyclic drive signal to the induction motor, the frequency of said drive signal at least partially determining the rate of motion of said motor output member; means for initiating braking by reducing the frequency of said drive signal to thereby reduce the operating speed of the induction motor to a predetermined non-zero value; feedback control means for identifying the speed and position of the movable motor output member; and means responsive to the feedback control means for stopping the induction motor by converting said cyclic drive signal to a DC signal when the movable member slows to a predetermined speed and reaches a predetermined position, the predetermined speed and position of said movable output member upon application of the DC signal causing said member to move a predetermined distance after application of said DC signal and stop precisely at a predetermined position.
Claim 2
Dependent Claim
164 words
A precision-stop control circuit for controlling an electric induction motor having a movable output member, said circuit comprising: means for providing a cyclic drive signal to the induction motor, the frequency of said drive signal at least partially determining the rate of motion of said motor output member; means for initiating braking by reducing the frequency of said drive signal to thereby reduce the operating speed of the induction motor to a predetermined non-zero value; feedback control means for identifying the speed and position of the movable motor output member; and means responsive to the feedback control means for stopping the induction motor by converting said cyclic drive signal to a DC signal when the movable member slows to a predetermined speed and reaches a predetermined position, the predetermined speed and position of said movable output member upon application of the DC signal causing said member to move a predetermined distance after application of said DC signal and stop precisely at a predetermined position.
Claim 3
Dependent Claim
55 words
The control circuit of claim 1 in which: the circuit further includes timing means responsive to the initial application of said DC signal to the induction motor for removing said DC signal from said induction motor after a predetermined interval to prevent said DC signal from damaging said motor after stopping said movable output member.
Claim 4
Dependent Claim
170 words
The control circuit of claim 2 in which: said brake initiating means comprise means for providing a variable frequency control signal; said drive signal providing means comprise voltage source means responsive to said control signal for providing a DC electric signal having a voltage level determined by the frequency of said control signal; and switching means coupling said voltage source means to the induction motor for switching the direction that the signal from said voltage source flows through said induction motor to thereby convert said DC signal to an AC induction motor drive signal, said switching means being responsive to said control signal and switching the direction of flow through the induction motor at a rate determined by the frequency of said control signal; and said means for converting said cyclic drive signal to a DC signal comprise gating means responsive to said feedback control means for blocking said control signal from said switching means to thereby fix the direction of flow of said drive signal through said induction motor.
Claim 5
Dependent Claim
159 words
The control circuit of claim 1 in which said feedback control means comprise: means for providing a cyclic motor speed signal having a frequency representing the rate of motion of said movable motor output member; signal generator means for providing a reference signal having a frequency representing a predetermined rate of motion; speed-identifying means for comparing the frequencies of said motor speed and reference signal and providing an enabling output signal when the frequency of said motor speed signal is less than that of said reference signal; and position-identifying means for counting the cycles of said feedback signal and providing an enabling output signal when the count equals a predeteRmined value; and said means for converting said cyclic drive signal to a DC signal is connected to said speed-identifying means and said position-identifying means and requires receipt of said enabling signals from both said speed-identifying means and said position-identifying means to provide said DC signal to the induction motor.
Claim 6
Dependent Claim
54 words
The control circuit of claim 4 in which: the circuit includes means for providing a brake command signal to said signal converting means; and said signal converting means include gating means requiring receipt of said brake command signal as well as said enabling signals to convert said cyclic drive signal to a DC signal.
Claim 7
Dependent Claim
46 words
The control circuit of claim 1 further including peripheral control means responsive to said feedback control means for providing a predetermined command signal to apparatus peripheral to the induction motor when the movable motor output member slows to a predetermined speed and reaches a predetermined position.
Claim 8
Dependent Claim
96 words
The control circuit of claim 6 in which: said peripheral control means comprise means for providing said predetermined command signal when the movable motor output member is at a position displaced from the position at which said signal converting means converts said cyclic drive signal to a DC signal, to thereby permit reduction of the operating speed of the induction motor, alteration of the operation of peripheral apparatus when said movable motor output member is in a predetermined position, and precise stopping of said movable motor output member, to all be achieved in a rapid sequence.
Claim 9
Dependent Claim
212 words
The control circuit of claim 6 in which: said feedback control means comprise: means for providing a first output signal to both said signal converting means and said peripheral control means when the movable motor output member slows to a predetermined speed; means for providing a second output signal to said peripheral control means when the movable motor output member is in a first predetermined position; and means for providing a third output signal to said signal converting means when said movable motor output member is in a second predetermined position; said peripheral control means comprise means for providing said predetermined command signal upon receipt of said first and second signals from said feedback control means; and said signal converting means comprise means for converting said cyclic drive signal to a DC signal upon receipt of said first and third signals from said feedback control means; said brake initiating means, said feedback control means, said means for activating peripheral apparatus, and said signal converting means thereby together permitting a reduction in the operating speed of the induction motor, the alteration of operation of peripheral apparatus when the movable motor output is in a predetermined position, and the precise stopping of said movable output member, to all be achieved in a rapid sequence.
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) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |