US3864610A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Speed control device for brushless dc motor
Assignee: Fuji Electric Co Ltd
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Filing: 1973-06-28
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Granted: 1975-02-04
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Expires: 1993-06-28
Abstract
Abstract A brushless d.c. motor is provided with a permanent magnet rotor and N''s stator windings separated in space by 360*/N. A transistor is connected in series with each winding. A Hall element is connected to the base of each transistor. The magnetic field of the rotor controls the Hall voltages of the Hall elements so that the transistors are rendered conducting at intervals separated by 360*/N. Each transistor remains conducting for a period of 180* to energize its associated stator winding. A speed detecting circuit including a capacitor is connected to one of phase windings so that the capacitor is charged to a voltage corresponding to the motor speed. As the motor speed varies, the corresponding change in capacitor voltage is used to control the conduction of the transistors, and thereby the current flowing through the windings, so that the motor speed is returned to a preset value.
Inventors
- 👤 Nobuhiko Kawamoto
- 👤 Tositaka Nakajima
- 👤 Tomoyuki Okubo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:43
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
130 words
A speed control device for a brushless d.c. electric motor including a permanent magnet rotor and a stator having stator winding means energized by a d.c. power supply, comprising switch means for controlling the energizing phase of said stator winding means in response to the rotary position of the rotor, means for detecting the energizing time period of said stator winding means, means for converting the detected period to a corresponding voltage amplitude, means for comparing the converted voltage amplitude with a preset voltage amplitude corresponding to a set speed to produce an error signal for controlling the amplitude of the current in said stator winding means in response to the difference between said converted voltage amplitude and said preset voltage to maintain the motor speed at said set speed.
Claim 2
Dependent Claim
130 words
A speed control device for a brushless d.c. electric motor including a permanent magnet rotor and a stator having stator winding means energized by a d.c. power supply, comprising switch means for controlling the energizing phase of said stator winding means in response to the rotary position of the rotor, means for detecting the energizing time period of said stator winding means, means for converting the detected period to a corresponding voltage amplitude, means for comparing the converted voltage amplitude with a preset voltage amplitude corresponding to a set speed to produce an error signal for controlling the amplitude of the current in said stator winding means in response to the difference between said converted voltage amplitude and said preset voltage to maintain the motor speed at said set speed.
Claim 3
Dependent Claim
81 words
A speed control device as defined in claim 1 wherein said switch means comprises transistor means connected in series with said stator winding means, Hall element means connected to said transistor means and responsive to the magnetic field of said rotor to control the phase of conduction of said transistor means, said Hall element means being responsive to said error signal for controlling the degree of conduction of said transistor means, and thereby the current amplitude in said stator winding means.
Claim 4
Dependent Claim
41 words
A speed control device as defined in claim 2 wherein said detecting means comprises a capacitor coupled to said stator winding means so that the capacitor is charged to a voltage corresponding to said energizing time period of said winding means.
Claim 5
Dependent Claim
65 words
A speed control device as defined in claim 3 wherein said stator winding means comprises N stator windings physically separated by 360*/N, said transIstor means comprises a transistor connected in series with each stator winding, said Hall element means comprises a Hall element connected to the base of each transistor, and further comprising circuit means coupling said capacitor to only one of said stator windings.
Claim 6
Dependent Claim
43 words
A speed-controlled device as defined in claim 4 wherein said coupling circuit means comprises another transistor having its output terminals connected across said capacitor and its control terminal connected to said one stator winding for controlling the charging and discharging of said capacitor.
Claim 7
Dependent Claim
55 words
A speed-controlled device as defined in claim 4 wherein said coupling circuit means comprises another transistor having its output terminals connected across said capacitor and its control terminal connected to the Hall element connected to the transistor which is in series with said one stator winding for controlling the charging and discharging of said capacitor.
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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |