US4982816A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Speed control system for elevators
Assignee: Otis Elevator Co
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Filing: 1989-04-18
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Granted: 1991-01-08
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Expires: 2009-04-18
Abstract
Abstract In an elevator provided with an inverter driven induction motor, output torque is determined by direct current of an inverter, slip frequency is determined from the thusly determined torque, the gap between an open-loop dictated speed pattern and the actual speed is compensated by the slip calculated during acceleration and constant speed movement, so that the open-loop control may be improved in terms of stop position precision.
Inventors
- 👤 Kazuhiko Doi
- 👤 Yasutami Kito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:35
CPC Classifications
B; B66; B66B; B66B1/00; B66B1/24; B66B1/28; B66B1/30; B66B1/285
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
117 words
A speed control system for an elevator employing an induction motor driven by an inverter, characterized in that it comprises a slip operation circuit, responsive to a sensed DC signal having a magnitude indicative of DC power input to the inverter, for providing a slip frequency signal; and a control device, responsive to a dictated speed profile signal and to said slip frequency signal, for determining output torque and load torque of the motor from said slip frequency and for determining the actual rotating speed of the motor from said torque determinations for providing inverter frequency and voltage control signals so as to make the actual speed identical to that dictated by said dictated speed profile signal.
Claim 2
Dependent Claim
117 words
A speed control system for an elevator employing an induction motor driven by an inverter, characterized in that it comprises a slip operation circuit, responsive to a sensed DC signal having a magnitude indicative of DC power input to the inverter, for providing a slip frequency signal; and a control device, responsive to a dictated speed profile signal and to said slip frequency signal, for determining output torque and load torque of the motor from said slip frequency and for determining the actual rotating speed of the motor from said torque determinations for providing inverter frequency and voltage control signals so as to make the actual speed identical to that dictated by said dictated speed profile signal.
Claim 3
Dependent Claim
20 words
The system of claim 1, wherein said slip frequency signal is sampled during the acceleration and the constant speed movement.
Claim 4
Dependent Claim
55 words
The system of claim 2, wherein at a selected deceleration starting position, the control device provides inverter frequency and voltage control signals for making the actual speed pattern identical to the speed dictated by said speed profile signal by control of the slip frequency according to said load torque determined during said constant speed movement.
References Cited (Backward Citations)
US4330741A
Cited
US4366427A
Cited
US4483419A
Cited
US4600088A
Cited
US4602701A
Cited
US4625834A
Cited
US4677361A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-01-07 | 1994-07-09 | 1995-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-07 | 1998-07-09 | 1999-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-07 | 2002-07-09 | 2003-01-08 | $7700.00 | Window Closed / Lapsed |