US3667018A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Brushless dc motor having electronic commutation responsive to rotor position and induced armature winding voltage
Assignee: Unisys Corp
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Filing: 1970-09-28
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Granted: 1972-05-30
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Expires: 1990-09-28
Abstract
Abstract A single sensor brushless DC motor contains two windings that are alternately energized to sustain rotor rotation and includes transistor switches in series with each motor winding. The transistor in series with the first winding is driven directly from the sensor so as to energize the first winding when the sensor is illuminated and that transistor is driven into saturation. The transistor in series with the second winding has an input terminal coupled to the first motor winding so as to react to voltages induced in the first winding during times when the first winding is de-energized.
Inventors
- 👤 Rodney G Rakes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:42
CPC Classifications
H; H02; H02K; H02K29/00; H02K29/06; H02K29/10
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
202 words
An improved switching circuit for a single sEnsor brushless DC motor, said motor being of the type containing first and second stator windings energizable from a DC source and arranged to provide magnetic fields in first and second diametrically opposed directions respectively, a permanently magnetized rotor rotatable in response to magnetic fields established by said stator windings and means to actuate said sensor when and only when said rotor is positioned within a predetermined semicircular sector, said improved switching circuit comprising means connecting one end of each of said stator windings to one side of said DC source, first and second switching means for optionally connecting the other end of said first and second stator windings respectively to the other side of said DC source, first means for driving said first switching means directly from said sensor, said first means being arranged to close said first switching means when said sensor is actuated, and second means for driving said second switching means in response to voltages appearing at said other end of said first stator winding, said second means including a voltage divider proportioned to close said second switching means only when said voltages exceed the voltage level of said DC source.
Claim 2
Dependent Claim
202 words
An improved switching circuit for a single sEnsor brushless DC motor, said motor being of the type containing first and second stator windings energizable from a DC source and arranged to provide magnetic fields in first and second diametrically opposed directions respectively, a permanently magnetized rotor rotatable in response to magnetic fields established by said stator windings and means to actuate said sensor when and only when said rotor is positioned within a predetermined semicircular sector, said improved switching circuit comprising means connecting one end of each of said stator windings to one side of said DC source, first and second switching means for optionally connecting the other end of said first and second stator windings respectively to the other side of said DC source, first means for driving said first switching means directly from said sensor, said first means being arranged to close said first switching means when said sensor is actuated, and second means for driving said second switching means in response to voltages appearing at said other end of said first stator winding, said second means including a voltage divider proportioned to close said second switching means only when said voltages exceed the voltage level of said DC source.
Claim 3
Dependent Claim
99 words
The switching circuit of claim 1 wherein said first and second switching means each include a transistor having base, collector and emitter electrodes, said transistors being connected so that their collector-emitter circuits are in series with the respective stator windings and wherein said voltage divider includes a first resistor connected directly between the base electrode of the transistor in said second switching means and the collector electrode of the transistor in said first switching means, said voltage divider further including a second resistor connected directly between the base and emitter electrodes of the transistor in said second switching means.
Claim 4
Dependent Claim
33 words
The switching circuit of claim 2 wherein the single sensor is a photosensor and the means to actuate the sensor includes a semicircular light shield mounted so as to rotate with said rotor.
Claim 5
Dependent Claim
87 words
The switching circuit of claim 3 wherein the photosensor is connected in a series configuration across said DC power supply, said series configuration including a resistor having one end connected to said other side of the DC power supply, and wherein said first means includes means connecting the base electrode of the transistor in said first switching means to the other end of said resistor, said resistor having a magnitude such that it developes a voltage sufficient to saturate the transistor only when said photosensor is illuminated.
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) | 1975-05-30 | 1975-11-29 | 1976-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-30 | 1979-11-29 | 1980-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-30 | 1983-11-29 | 1984-05-30 | $7700.00 | Window Closed / Lapsed |