US5021724A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Controlling apparatus for induction motor
Assignee: Hitachi Ltd
•
Filing: 1990-11-07
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Granted: 1991-06-04
•
Expires: 2010-11-07
Abstract
Abstract A controlling apparatus for an induction motor for controlling the induction motor in high efficiency having a converter for supplying an electric power to the induction motor, a rotational speed detector of the induction motor, a controlling means of the converter for holding a torque of the induction motor constant while the rotational speed of the induction motor is lower than a base rotational speed and to decrease a secondary magnetic flux of the induction motor according to the rotational speed while the rotational speed of the induction motor is over the base rotational speed, and a means for varying the secondary magnetic flux according to a terminal voltage of the induction motor so as to hold the terminal voltage a predetermined constant voltage while the rotational speed of the induction motor is higher than the predetermined speed.
Inventors
- 👤 Yasuhiro Hirano
- 👤 Mitunori Yamashina
- 👤 Tetsuo Etoh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:39
CPC Classifications
H; H02; H02P; H02P21/00; H02P21/06; H02P21/08; Y; Y02; Y02P; Y02P80/00; Y02P80/10
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
136 words
A controlling apparatus for an induction motor comprising, an induction motor, a converter for supplying an electric power to the induction motor, a detector for detecting a rotational speed of the induction motor, a means for controlling the converter so as to hold a torque of the induction motor constant while the rotational speed of the induction motor is lower than a predetermined speed and to decrease a secondary magnetic flux of the induction motor according to the rotational speed while the rotational speed of the induction motor is over the predetermined speed, and a means for varying the secondary magnetic flux according to a terminal voltage of the induction motor so as to hold the terminal voltage a predetermined constant voltage while the rotational speed of the induction motor is higher than the predetermined speed.
Claim 2
Dependent Claim
136 words
A controlling apparatus for an induction motor comprising, an induction motor, a converter for supplying an electric power to the induction motor, a detector for detecting a rotational speed of the induction motor, a means for controlling the converter so as to hold a torque of the induction motor constant while the rotational speed of the induction motor is lower than a predetermined speed and to decrease a secondary magnetic flux of the induction motor according to the rotational speed while the rotational speed of the induction motor is over the predetermined speed, and a means for varying the secondary magnetic flux according to a terminal voltage of the induction motor so as to hold the terminal voltage a predetermined constant voltage while the rotational speed of the induction motor is higher than the predetermined speed.
Claim 3
Dependent Claim
49 words
A controlling apparatus for an induction motor as defined in claim 1 characterized in that, said means for varying the secondary magnetic flux calculates a peak value of the terminal voltage of the induction motor which is detected and varies the secondary magnetic flux based on the peak value.
Claim 4
Dependent Claim
53 words
A controlling apparatus for an induction motor as defined in claim 1 characterized in that, said means for varying the secondary magnetic flux is a simulator for simulating the secondary magnetic flux according to the terminal voltage so as to hold the terminal voltage the predetermined constant voltage by detecting the rotational speed.
Claim 5
Dependent Claim
39 words
A controlling apparatus for an induction motor as defined in claim 1 characterized in that, said means for varying the secondary magnetic flux detects load of the induction motor and varies the secondary magnetic flux based on the load.
Claim 6
Dependent Claim
48 words
A controlling apparatus for an induction motor as defined in claim 1 characterized in that, said means for varying the secondary magnetic flux holds the terminal voltage to a maximum output voltage of the converter while the rotational speed of the induction motor is over the predetermined speed.
Claim 7
Dependent Claim
38 words
A controlling apparatus for an induction motor as defined in claim 1 characterized in that, said mans for varying the secondary magnetic flux varies the secondary magnetic flux according to a detected terminal voltage of the induction motor.
Claim 8
Dependent Claim
37 words
A controlling apparatus for an induction motor as defined in claim 1 characterized in that, said means for varying the secondary magnetic flux varies the secondary magnetic flux according to an ordering output voltage of the converter.
References Cited (Backward Citations)
US4292531A
Cited
US4361794A
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JPS6014593A
Cited
US4680526A
Cited
US4818927A
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US4792741A
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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) | 1994-06-03 | 1994-12-03 | 1995-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-06-03 | 1998-12-03 | 1999-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-06-03 | 2002-12-03 | 2003-06-04 | $7700.00 | Window Closed / Lapsed |