US3887852A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control system for rotating electrical machinery using electronically derived injected rotor EMF{3 s
Assignee: Individual
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Filing: 1973-12-13
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Granted: 1975-06-03
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Expires: 1993-12-13
Abstract
Abstract A unique means for automatic closed-loop speed and power factor regulation, both below and above synchronous speed, using electronically derived, rotor injected EMF''s for rotating electrical machinery, with no power pulsations, and smooth continuous control is described. EMF''s of the correct frequency are electronically derived and modulated to the appropriate amplitude, without the use of a current transformer and its associated saturation problems, using feedback signals from a speed transducer for comparison with a reference signal for master control. This arrangement allows independent setting of the speed and rotor power factor angle. Speed regulation at the desired setting is maintained through feedback controls. Unlike previous art this technique allows speed control beyond synchronous speed, with no torque pulsations, minimum rotor power loss and also allows elimination of slip rings. The invention may also be employed in other forms of rotary electrical machinery including d.c. and single phase a.c.
Inventors
- 👤 Roosevelt A Fernandes
- 👤 Harry R Sanders
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:02
CPC Classifications
H; H02; H02P; H02P25/00; H02P25/16; H02P25/24; H02P25/26
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
149 words
A control system for AC machinery comprising: a. a source of three-phase power providing a controlled reference signal; b. means for sensing the frequency of the currents in each of the three rotor phases; c. means for generating square wave signals of the respective frequencies and phases of each rotor phase in response tO signals received from said sensing means; d. means for generating a signal commensurate with actual rotational speed of the machine; e. means for selectively varying said reference signal; f. means for comparing said signal commensurate with actual rotational speed and said varied reference signal and providing an amplified difference signal output; g. means for dividing said signal output into equal positive and negative signal levels; h. means for clamping said signal levels at predetermined amplitude levels; and i. means for applying said clamped signal levels to the respective rotor windings at the required current level.
Claim 2
Dependent Claim
149 words
A control system for AC machinery comprising: a. a source of three-phase power providing a controlled reference signal; b. means for sensing the frequency of the currents in each of the three rotor phases; c. means for generating square wave signals of the respective frequencies and phases of each rotor phase in response tO signals received from said sensing means; d. means for generating a signal commensurate with actual rotational speed of the machine; e. means for selectively varying said reference signal; f. means for comparing said signal commensurate with actual rotational speed and said varied reference signal and providing an amplified difference signal output; g. means for dividing said signal output into equal positive and negative signal levels; h. means for clamping said signal levels at predetermined amplitude levels; and i. means for applying said clamped signal levels to the respective rotor windings at the required current level.
Claim 3
Dependent Claim
149 words
A control system for AC machinery comprising: a. a source of three-phase power providing a controlled reference signal; b. means for sensing the frequency of the currents in each of the three rotor phases; c. means for generating square wave signals of the respective frequencies and phases of each rotor phase in response tO signals received from said sensing means; d. means for generating a signal commensurate with actual rotational speed of the machine; e. means for selectively varying said reference signal; f. means for comparing said signal commensurate with actual rotational speed and said varied reference signal and providing an amplified difference signal output; g. means for dividing said signal output into equal positive and negative signal levels; h. means for clamping said signal levels at predetermined amplitude levels; and i. means for applying said clamped signal levels to the respective rotor windings at the required current level.
Claim 4
Dependent Claim
149 words
A control system for AC machinery comprising: a. a source of three-phase power providing a controlled reference signal; b. means for sensing the frequency of the currents in each of the three rotor phases; c. means for generating square wave signals of the respective frequencies and phases of each rotor phase in response tO signals received from said sensing means; d. means for generating a signal commensurate with actual rotational speed of the machine; e. means for selectively varying said reference signal; f. means for comparing said signal commensurate with actual rotational speed and said varied reference signal and providing an amplified difference signal output; g. means for dividing said signal output into equal positive and negative signal levels; h. means for clamping said signal levels at predetermined amplitude levels; and i. means for applying said clamped signal levels to the respective rotor windings at the required current level.
Claim 5
Dependent Claim
42 words
The invention according to claim 1 and further including a solenoidal winding on each of the stator and rotor of the machine for each of the three phases for voltage transfer between stationary and moving parts, thereby eliminating the need for brushes.
Claim 6
Dependent Claim
24 words
The invention according to claim 2 wherein at least a portion of said varying means is carried on a rotating portion of the machine.
Claim 7
Dependent Claim
19 words
The invention according to claim 3 wherein said varying means includes a light source and means electrically responsive thereto.
Claim 8
Dependent Claim
21 words
The invention according to claim 4 wherein said means for generating a signal commensurate with actual speed comprises a tachometer generator.
Claim 9
Dependent Claim
150 words
A control system for a rotary electrical machine having a stator and a rotor, each with windings forming separate circuits, said system comprising, in combination: a. a source of electrical power providing a reference voltage; b. means for selectively varying said reference voltage; c. means for generating a first signal proportional to actual rotational speed of the machine; d. means for comparing said varied reference voltage with said first signal and providing a difference signal output; e. means for amplifying said difference signal by a predetermined gain to provide a second signal; f. means for deriving from the rotor circuit a third signal, commensurate with rotor frequency and phase; g. means for amplifying said third signal by a predetermined gain; and h. means for applying to the rotor circuit an injected voltage comprising a portion of said third signal selected as a function of the amplitude of said second signal.
Claim 10
Dependent Claim
150 words
A control system for a rotary electrical machine having a stator and a rotor, each with windings forming separate circuits, said system comprising, in combination: a. a source of electrical power providing a reference voltage; b. means for selectively varying said reference voltage; c. means for generating a first signal proportional to actual rotational speed of the machine; d. means for comparing said varied reference voltage with said first signal and providing a difference signal output; e. means for amplifying said difference signal by a predetermined gain to provide a second signal; f. means for deriving from the rotor circuit a third signal, commensurate with rotor frequency and phase; g. means for amplifying said third signal by a predetermined gain; and h. means for applying to the rotor circuit an injected voltage comprising a portion of said third signal selected as a function of the amplitude of said second signal.
Claim 11
Dependent Claim
13 words
The invention according to claim 6 wherein said machine is a DC machine.
Claim 12
Dependent Claim
13 words
The invention according to claim 6 wherein said machine is an AC machine.
Claim 13
Dependent Claim
30 words
The invention according to claim 8 and further including means for applying said injected voltage in a predetermined phase relationship to the induced rotor voltage, thereby effecting power factor control.
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) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |