US4543520A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Induction motor slip control
Assignee: Kollmorgen Technologies Corp
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Filing: 1983-12-30
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Granted: 1985-09-24
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Expires: 2003-12-30
Abstract
Abstract A variable frequency AC induction motor servo control system wherein slip is generated as a function of stator current. In a preferred embodiment the slip per ampere ratio is constant in the range from zero to approximately base speed and thereafter increases exponentially as the rotor speed increases above base speed.
Inventors
- 👤 George E. Danz
- 👤 C. Calvin Shuler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 19:44
CPC Classifications
H; H02; H02P; H02P23/00; H02P23/08
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
163 words
A servo control system for an AC induction motor comprising: a servo loop responsive to the speed of the AC induction motor and a desired speed indication to provide an error signal proportional to the difference between said speed indications; means providing a speed pulse train having a repetition rate proportional to the speed of the AC induction motor; a slip pulse generator for providing a slip pulse train, said slip pulse generator being responsive to an indication of motor excitation current, and to motor speed, so that the repetition rate of said slip pulse train is a function of both motor current and motor speed; means providing a digital rotating vector indication in accordance with the summation of said speed pulse train and said slip pulse train; and conversion means for providing a synthesized sine wave excitation for the AC induction motor in accordance with the phase and frequency of said vector indication, and with an amplitude proportional to said error signal.
Claim 2
Dependent Claim
163 words
A servo control system for an AC induction motor comprising: a servo loop responsive to the speed of the AC induction motor and a desired speed indication to provide an error signal proportional to the difference between said speed indications; means providing a speed pulse train having a repetition rate proportional to the speed of the AC induction motor; a slip pulse generator for providing a slip pulse train, said slip pulse generator being responsive to an indication of motor excitation current, and to motor speed, so that the repetition rate of said slip pulse train is a function of both motor current and motor speed; means providing a digital rotating vector indication in accordance with the summation of said speed pulse train and said slip pulse train; and conversion means for providing a synthesized sine wave excitation for the AC induction motor in accordance with the phase and frequency of said vector indication, and with an amplitude proportional to said error signal.
Claim 3
Dependent Claim
37 words
In a servo control system according to claim 1 wherein said repetition rate of said slip pulse train is a linear function of excitation current below base speed for the motor and increases exponentially above base speed.
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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) | 1988-09-23 | 1989-03-25 | 1989-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-23 | 1993-03-25 | 1993-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-23 | 1997-03-25 | 1997-09-24 | $7700.00 | Window Closed / Lapsed |