Patent US5225759A successfully refreshed from Google Patents.
US5225759A
Expired / Lapsed
US
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Starting and control method for brushless DC motor
Assignee: Nidec Corp
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Filing: 1989-03-14
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Granted: 1993-07-06
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Expires: 2009-03-14
Abstract
Abstract Starting, accelerating and rated rotation of a rotor is carried out without any detector for the rotor position. A motor is controlled with an openloop circuit a short time in a starting area of low speed rotation, and thus the motor can be certainly started. In a rated rotation area, turning timing of the motor is precisely controlled by detecting counter-electromotive force of a stator coil.
Inventors
- 👤 Mineyo Endo
- 👤 Yosuke Kawate
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:21
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/14; H02P6/16; H02P6/18; H02P6/182; H02P6/20; H02P6/21
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
133 words
A method for starting a brushless DC motor which includes a stator for generating an electromagnetic field and a permanent magnet rotor, the method comprising: exciting the stator with an open loop control and driving the motor with a bipolar mode drive circuit to initiate rotation of the rotor, detecting counter-electromotive force in at least one coil of the stator, deriving a control signal from the detected counter-electromotive force and related in phase thereto, accelerating the rotation in accord with the control signal, when rotation frequency reaches a first predetermined number shifting the phase of the control signal and continuing acceleration; and when rotation frequency reaches a second predetermined number switching the drive circuit from bipolar mode to unipolar mode and continuing acceleration to reach the rated value of rotation for the motor.
Claim 2
Independent Claim
133 words
A method for starting a brushless DC motor which includes a stator for generating an electromagnetic field and a permanent magnet rotor, the method comprising: exciting the stator with an open loop control and driving the motor with a bipolar mode drive circuit to initiate rotation of the rotor, detecting counter-electromotive force in at least one coil of the stator, deriving a control signal from the detected counter-electromotive force and related in phase thereto, accelerating the rotation in accord with the control signal, when rotation frequency reaches a first predetermined number shifting the phase of the control signal and continuing acceleration; and when rotation frequency reaches a second predetermined number switching the drive circuit from bipolar mode to unipolar mode and continuing acceleration to reach the rated value of rotation for the motor.
Claim 3
Dependent Claim
26 words
A method for starting a brushless DC motor as in claim 1, wherein the phase of the control signal is shifted by switching control signal timing.
Claim 4
Dependent Claim
26 words
A method for starting a brushless DC motor as in claim 1 wherein the phase of the control signal is shifted by changing a filter constant.
Claim 5
Dependent Claim
26 words
A method for starting a brushless DC motor as in claim 2 wherein the phase of the control signal is shifted by changing a filter constant.
References Cited (Backward Citations)
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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) | 1996-07-05 | 1997-01-04 | 1997-07-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-07-05 | 2001-01-04 | 2001-07-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-07-05 | 2005-01-04 | 2005-07-06 | $7700.00 | Window Closed / Lapsed |