US3840790A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronically commutated motor
Assignee: AC MATERIAL HANDLING Corp 777 MANOR PARK DRIVE COLUMBUS OHIO 43228 A CORP OHIO
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Filing: 1972-08-07
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Granted: 1974-10-08
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Expires: 1992-08-07
Abstract
Abstract A n-phase electronically commutated motor has a stator with n angularly displaced phase windings, each of which comprises a pair of power windings, and 2n drive windings each of which is inductively coupled to one of the power windings. Each power winding is connected in series with a transistor power switch across an electric power source so that the power windings of each phase generate magnetic fluxes in opposite directions and operate in push-pull. A capacitive rotor sensor coupled to the motor rotor derives n-phase square wave rotor position signals displaced 360/n degrees apart at a frequency proportional to rotor speed, and n sets of logic gates receive the rotor position signals and control the conduction interval of the power transistors. The logic gates are opened during rotor position signals which energize the power switches in a sequence that generates a rotating magnetic field within the stator. A base drive transistor is connected between the base of each transistor power switch and the associated drive winding, and current is fed back from the associated inductively linked power and drive windings through the base drive transistor to sustain conduction of the power switch.
Inventors
- 👤 F Stich
- 👤 G Schwantes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:06
CPC Classifications
H; H02; H02P; H02P6/00; H02P6/14; H02P6/08
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
186 words
An electronic commutation system comprising, in combination, an electric motor having a ferromagnetic stator provided with n phase power windings displaced 360/n degrees apart, where n is an integer greater than one, a ferromagnetic rotor mounted for rotation within said stator, means for generating magnetic poles in said rotor, an electric power source, n transistor power switches each of which is in series with one of said power windings across said power source, means for deriving a plurality of time-displaced rotor position signals at a frequency which is a function of rotor angular velocity during rotation of said rotor through 360 electrical degrees each of which is indicative of a different position of said rotor within said stator, means for turning on each of said power switches during a different rotor position signal so that the magnetic field generated by said stator phase power windings rotates in synchronism with said rotor poles, and means including winding means on said stator inductively linked to stator phase power windings for supplying base drive to said transistor power switches when they are turned on by the rotor position signals.
Claim 2
Dependent Claim
186 words
An electronic commutation system comprising, in combination, an electric motor having a ferromagnetic stator provided with n phase power windings displaced 360/n degrees apart, where n is an integer greater than one, a ferromagnetic rotor mounted for rotation within said stator, means for generating magnetic poles in said rotor, an electric power source, n transistor power switches each of which is in series with one of said power windings across said power source, means for deriving a plurality of time-displaced rotor position signals at a frequency which is a function of rotor angular velocity during rotation of said rotor through 360 electrical degrees each of which is indicative of a different position of said rotor within said stator, means for turning on each of said power switches during a different rotor position signal so that the magnetic field generated by said stator phase power windings rotates in synchronism with said rotor poles, and means including winding means on said stator inductively linked to stator phase power windings for supplying base drive to said transistor power switches when they are turned on by the rotor position signals.
Claim 3
Dependent Claim
84 words
In the combination of claim 1 wherein each transistor power switch has its emitter-collector circuit in series with one of said power windings, and said means for supplying base drive includes n drive windings on said stator each of which is mutually coupled with one of said stator phase power windings so that current is regeneratively fed back from the inductively related power and drive windings on the stator associated with said transistor power switches to sustain conduction thereby during said rotor position signals.
Claim 4
Dependent Claim
75 words
In the electronic commutation system of claim 2 wherein said means for supplying base drive forward biases said power transistor switches and includes a base drive transistor for each said power switch connected between said power switch and the associated drive winding, whereby base current is regeneratively fed back from the associated inductively linked phase power and drive windings through the associated base drive transistor to sustain conduction of the power switch for each phase.
Claim 5
Dependent Claim
98 words
In the electronic commutation system of claim 3 wherein said rotor position signal is coupled to the base of the associated base drive transistor and the base of each said power switch is connected through the emitter-collector circuit of the associated base drive transistor to the associated phase drive winding, and a diode is connected across the emitter and collector of each base drive transistor in opposite polarity thereto so that reverse bias is coupled to the base of the associated power switch when the polarity of the associated drive winding reverses upon turning off the power switch.
Claim 6
Dependent Claim
41 words
In the combination of claim 4 wherein each power switch includes a plurality of paralleled power transistors having their emitters commoned and their collectors commoned and their bases connected through similar resistors to the emitter of the associated base drive transistor.
Claim 7
Dependent Claim
81 words
In the combination of claim 2 wherein said power source is unidirectional and each said phase power winding has a center tap, and including 2n power transistor switches each of which is in series with said source and one of the stator phase power winding halves which are joined at a center tap, said power switches being connected so that the magnetic fluxes generated by the halves of each stator phase power winding are in opposite directions and oPerate in push-pull.
Claim 8
Dependent Claim
63 words
In the combination of claim 6 wherein the center taps of all said phase power windings are commoned, each said drive winding has a center tap, and each of the drive winding halves which are joined at the center tap is inductively linked with a power winding half of the corresponding phase, said center taps of all of said drive windings being commoned.
Claim 9
Dependent Claim
105 words
In the combination of claim 4 wherein said base drive is regeneratively fed back through said inductively linked phase power and drive windings and the emitter-collector circuit of the associated base drive transistor and is of sufficient magnitude to forward bias the associated power transistor switch in saturation when said rotor position signal turns it on, and wherein degenerative current limit turn-off of said power transistor switch by transformer action through said inductively linked power and drive windings and said diode occurs if the collector current of said power transistor switch becomes sufficiently high to pull it out of saturation and into the active region.
Claim 10
Dependent Claim
76 words
In the combination of claim 8 wherein removal of said rotor position signal turns off the associated base drive transistor so that regenerative feedback can no longer support the associated power transistor switch in saturation and the consequent increase of its collector-to-emitter voltage and reversal of the polarity of said associated drive winding results in reverse bias being degeneratively fed back through said diode to the base of said power transistor switch to turn it off.
Claim 11
Dependent Claim
70 words
In the combination of claim 4 and including drive oscillator means for applying a succession of narrow forward bias pulses through the emitter-collector circuit of said base drive transistor to the base of the associated transistor power switch during said rotor position signal to defeat reverse bias to and re-initiate conduction thereby, each of said narrow pulses being of sufficient magnitude to operate the associated power transistor switch in saturation.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-07 | 1978-04-08 | 1978-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-07 | 1982-04-08 | 1982-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-07 | 1986-04-08 | 1986-10-08 | $7700.00 | Window Closed / Lapsed |