US3854077A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Induction motor system with constant torque
Assignee: WM LEAR ENTERPRISES Inc
•
Filing: 1973-01-31
•
Granted: 1974-12-10
•
Expires: 1993-01-31
Abstract
Abstract An electric induction motor/control system that provides the desirable high starting torque and wide speed characteristics of direct current motors. The stator of the induction motor has two specially interrelated winding sets per phase. The motor windings are supplied with unidirectional current pulses from silicon controlled rectifiers that are programmed to provide advantageous modes of operation for the motor. The unique relation and interaction between the motor windings hereof and the associated electronic circuitry results in high power factor, good efficiency, and self-clearing SCR commutation action. The preferred motors use a squirrel cage rotor with no commutator, brushes, or slip rings. The complementary stator winding arrangements are not voltage limited, and thereby permit the construction of large power motor systems. Practical motor ratings are from fractional to over 500 horsepower, at speeds ranging from 600 to 40,000 rpm, and higher. The electronic control sections for even the high horsepower motors are operated at low voltage and with few watts. Control circuitry is provided that can operate the motor systems: (a) at constant output torque over a wide speed range; (b) at constant horsepower over a selected speed range; (c) with traction output characteristics similar to that of series motors; (d) at constant speed; (e) and with direct speed reversal in any of these modes. These motor systems require little maintenance, and may be hermetically sealed.
Inventors
- 👤 J Greenwell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 01:35
CPC Classifications
H; H02; H02P; H02P23/00; H02P23/28
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
198 words
A polyphase motor system comprising a stator and an induction rotor, said stator containing a plurality of half-phase windings in paired consequent pole array with one pair for each effective phase for the motor in polyphase operation, a controlled rectifier for each of said half-phase windings, control means connected with said controlled rectifiers to selectively establish conduction periods therefor and thereby for their associated half-phase windings to provide a rotating magnetic field in the stator for corresponding operation of said induction rotor, said control means including a timing circuit that effects said successive conduction periods in related spaced time intervals among said half-phase windings once during each cycle of applied Motor frequency, said timing circuit having an electronic clock, circuit means coupled to said clock and arranged to control its frequency and thereby the duration of said conduction periods, and electrical means providing a variable source of operating dc voltage for said half-phase windings, said circuit means including a Zener diode, said variable dc voltage being coupled to said Zener diode and thereby to said clock, whereby variation of the applied dc voltage from the source directly produces ranges of substantially constant torque output operation of the rotor.
Claim 2
Dependent Claim
198 words
A polyphase motor system comprising a stator and an induction rotor, said stator containing a plurality of half-phase windings in paired consequent pole array with one pair for each effective phase for the motor in polyphase operation, a controlled rectifier for each of said half-phase windings, control means connected with said controlled rectifiers to selectively establish conduction periods therefor and thereby for their associated half-phase windings to provide a rotating magnetic field in the stator for corresponding operation of said induction rotor, said control means including a timing circuit that effects said successive conduction periods in related spaced time intervals among said half-phase windings once during each cycle of applied Motor frequency, said timing circuit having an electronic clock, circuit means coupled to said clock and arranged to control its frequency and thereby the duration of said conduction periods, and electrical means providing a variable source of operating dc voltage for said half-phase windings, said circuit means including a Zener diode, said variable dc voltage being coupled to said Zener diode and thereby to said clock, whereby variation of the applied dc voltage from the source directly produces ranges of substantially constant torque output operation of the rotor.
Claim 3
Dependent Claim
51 words
A polyphase motor system as claimed in claim 1, in which said half-phase windings are arrayed about the stator with substantially equal magnetic and physical separation between adjacent windings, associated windings of each pair being respectively interconnected into two symmetrical polyphase winding groups that are 180* apart magnetically in the stator.
Claim 4
Dependent Claim
38 words
A polyphase motor system as claimed in claim 1, in which said control means establishes the said conduction periods at respective 180* electrical separation between related half-phase pairs and thereby provide said rotating magnetic field in the stator.
Claim 5
Dependent Claim
44 words
A polyphase motor system as claimed in claim 2, in which said control means establishes the said controlled rectifier conduction periods at respective 180* electrical separation between related half-phase pairs in said winding groups and thereby provide said rotating magnetic field in the stator.
Claim 6
Dependent Claim
54 words
A polyphase motor system as claimed in claim 2, in which said half-phase windings are arrayed in the stator with relatively low mutual magnetic induction between the windings of respective pairs, whereby magnetic interaction among said stator windings cyclically effects self-clearing of the controlled rectifier conductions should any extend beyond its predetermined conduction period.
Claim 7
Dependent Claim
55 words
A polyphase motor system as claimed in claim 1, in which said electronic clock includes a uni-junction transistor, said Zener diode being connected between said variable dc source and the emitter of said unijunction transistor to correspondingly overcome the internal IZ voltage drop in the motor and thereby effect the said constant torque output characteristic.
Claim 8
Dependent Claim
46 words
A polyphase motor system as claimed in claim 1, in which said circuit means further includes an adjustable resistor connected between said variable dc source and the Zener diode for presetting the horsepower rating of the rotor output during its corresponding said constant torque operation characteristic.
Claim 9
Dependent Claim
46 words
A polyphase motor system as claimed in claim 6, in which said circuit means further includes an adjustable resistor connected between said variable dc source and the Zener diode for presetting the horsepower rating of the rotor output during its corresponding said constant torque operation characteristic.
Claim 10
Dependent Claim
50 words
A polyphase motor system as claimed in claim 7, further including a capacitor connected between the Zener diode terminal with the adjustable resistor and ground potential, the capacitance of said capacitor being adjustable to provide a desired rate of acceleration for the motor system as well as its deceleration rate.
Claim 11
Dependent Claim
24 words
A polyphase motor system as claimed in claim 9, further including a second capacitor with preset capacitance connected between said emitter and ground potential.
References Cited (Backward Citations)
US3753060A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-09 | 1978-06-10 | 1978-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-09 | 1982-06-10 | 1982-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-09 | 1986-06-10 | 1986-12-10 | $7700.00 | Window Closed / Lapsed |