US3908161A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Field excitation system for synchronous machines utilizing a rotating transformer brushless exciter generating combination
Assignee: General Electric Co
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Filing: 1974-02-07
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Granted: 1975-09-23
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Expires: 1994-02-07
Abstract
Abstract A field excitation system is provided for a synchronous machine which is operated both as a motor and as a generator. Field excitation is provided by a rotating machine which is connected as a brushless exciter when the synchronous machine is in the generating mode and connected as a rotating transformer when the synchronous machine is in the motoring mode. This conversion is achieved by selectively switching the field winding connections of the exciter/transformer and by switching the voltage applied to the field windings from DC to AC. When the main machine is to be operated in the motoring mode, a three-phase alternating voltage is applied to the exciter field winding and the field winding connections are switched so that the field windings are in a three-phase WYE connection and the machine functions as a rotating transformer. The alternating voltage induced in the rotor winding is rectified and provides field excitation for the main machine. As the main machine comes up to speed, a speed at which the machine is to be operated as a generator, the rotating machine is reconnected to operate as a brushless exciter generator. To this end, the field windings are connected in series, the three-phase alternating voltage is removed and a DC voltage is applied to the field windings. The exciter now operates as a standard inside-out synchronous exciter generator to generate a voltage in the armature rotor windings which is rectified to supply the DC field for the main machine rotor. In this fashion, DC excitation for the main synchronous machine is provided both when the machine is initially started from standstill in the motoring mode and when it switches to the generating mode.
Inventors
- 👤 Lawrence Waters Messenger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:32
CPC Classifications
F; F02; F02N; F02N11/00; F02N11/04; H; H02; H02K; H02K19/00
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
379 words
A dynamoelectric machine which is to be operated both as a D.C. brushless motor and as a synchronous generator and an excitation system therefor, the combination comprising: a. a dynamoelectric machine including 1. a rotating field winding mounted on a shaft, 2. stationary armature windings, means for applying alternating voltage to said armature windings when said dynamoelectric machine is operating as a D.C. brushless motor, b. an exciter mounted on the same shaft as the field windings of the dynamoelectric machine, said exciter including rotating armature windings and stationary field windings, c. means for rectifying the output from the rotating exciter armature windings to provide D.C. field excitation for the rotating field winding of said dynamoelectric machine both during operation of the dynamoelectric machine as a motor and as a synchronous generator, d. means for selectively operating said field as a rotating transformer when said dynamoelectric machine is operated as a motor to supply D.C. flux for said dynamoelectric machine when it operates as a motor and as an exciter generator when said dynamoelectric machine is driven as a generator to provide D.C. field excitation for the machine as a synchronous generator, said last named means including: 1. means for connecting said field winding in a polyphase connection and means for energizing the field winding with a polyphase A.C. signal to produce a flux wave in the air gap of said exciter to induce an alternating voltage in the armature windings when the dynamoelectric machine is operated as a motor said alternating voltage being rectified in said rectifying means to provide excitation for the field windings and D.C. flux for the dynamoelectric machine whereby said dynamoelectric machine functions as a motor to drive a load, and 2. means for changing the energization of the exciter field winding to establish a D.C. field across the exciter air gap to generate an alternating voltage in the armature winding when the dynamoelectric machine is driven as a generator including means for reconnecting all of the polyphase windings in series and means to impress a D.C. voltage across said series connected field whereby said exciter provides D.C. field excitation for the dynamoelectric machine during generator operation and also provides D.C. flux when the machine operates as a motor from standstill up to speed.
Claim 2
Dependent Claim
379 words
A dynamoelectric machine which is to be operated both as a D.C. brushless motor and as a synchronous generator and an excitation system therefor, the combination comprising: a. a dynamoelectric machine including 1. a rotating field winding mounted on a shaft, 2. stationary armature windings, means for applying alternating voltage to said armature windings when said dynamoelectric machine is operating as a D.C. brushless motor, b. an exciter mounted on the same shaft as the field windings of the dynamoelectric machine, said exciter including rotating armature windings and stationary field windings, c. means for rectifying the output from the rotating exciter armature windings to provide D.C. field excitation for the rotating field winding of said dynamoelectric machine both during operation of the dynamoelectric machine as a motor and as a synchronous generator, d. means for selectively operating said field as a rotating transformer when said dynamoelectric machine is operated as a motor to supply D.C. flux for said dynamoelectric machine when it operates as a motor and as an exciter generator when said dynamoelectric machine is driven as a generator to provide D.C. field excitation for the machine as a synchronous generator, said last named means including: 1. means for connecting said field winding in a polyphase connection and means for energizing the field winding with a polyphase A.C. signal to produce a flux wave in the air gap of said exciter to induce an alternating voltage in the armature windings when the dynamoelectric machine is operated as a motor said alternating voltage being rectified in said rectifying means to provide excitation for the field windings and D.C. flux for the dynamoelectric machine whereby said dynamoelectric machine functions as a motor to drive a load, and 2. means for changing the energization of the exciter field winding to establish a D.C. field across the exciter air gap to generate an alternating voltage in the armature winding when the dynamoelectric machine is driven as a generator including means for reconnecting all of the polyphase windings in series and means to impress a D.C. voltage across said series connected field whereby said exciter provides D.C. field excitation for the dynamoelectric machine during generator operation and also provides D.C. flux when the machine operates as a motor from standstill up to speed.
Claim 3
Dependent Claim
155 words
stationary armature windings, means for applying alternating voltage to said armature windings when said dynamoelectric machine is operating as a D.C. brushless motor, b. an exciter mounted on the same shaft as the field windings of the dynamoelectric machine, said exciter including rotating armature windings and stationary field windings, c. means for rectifying the output from the rotating exciter armature windings to provide D.C. field excitation for the rotating field winding of said dynamoelectric machine both during operation of the dynamoelectric machine as a motor and as a synchronous generator, d. means for selectively operating said field as a rotating transformer when said dynamoelectric machine is operated as a motor to supply D.C. flux for said dynamoelectric machine when it operates as a motor and as an exciter generator when said dynamoelectric machine is driven as a generator to provide D.C. field excitation for the machine as a synchronous generator, said last named means including:
Claim 4
Dependent Claim
155 words
stationary armature windings, means for applying alternating voltage to said armature windings when said dynamoelectric machine is operating as a D.C. brushless motor, b. an exciter mounted on the same shaft as the field windings of the dynamoelectric machine, said exciter including rotating armature windings and stationary field windings, c. means for rectifying the output from the rotating exciter armature windings to provide D.C. field excitation for the rotating field winding of said dynamoelectric machine both during operation of the dynamoelectric machine as a motor and as a synchronous generator, d. means for selectively operating said field as a rotating transformer when said dynamoelectric machine is operated as a motor to supply D.C. flux for said dynamoelectric machine when it operates as a motor and as an exciter generator when said dynamoelectric machine is driven as a generator to provide D.C. field excitation for the machine as a synchronous generator, said last named means including:
Claim 5
Dependent Claim
92 words
means for changing the energization of the exciter field winding to establish a D.C. field across the exciter air gap to generate an alternating voltage in the armature winding when the dynamoelectric machine is driven as a generator including means for reconnecting all of the polyphase windings in series and means to impress a D.C. voltage across said series connected field whereby said exciter provides D.C. field excitation for the dynamoelectric machine during generator operation and also provides D.C. flux when the machine operates as a motor from standstill up to speed.
Claim 6
Dependent Claim
92 words
means for changing the energization of the exciter field winding to establish a D.C. field across the exciter air gap to generate an alternating voltage in the armature winding when the dynamoelectric machine is driven as a generator including means for reconnecting all of the polyphase windings in series and means to impress a D.C. voltage across said series connected field whereby said exciter provides D.C. field excitation for the dynamoelectric machine during generator operation and also provides D.C. flux when the machine operates as a motor from standstill up to speed.
Claim 7
Dependent Claim
48 words
The excitation system according to claim 1 including means responsive to the speed of the dynamoelectric machine to switch the energization of the exciter field windings when the dynamoelectric machine reaches a predetermined speed at which its mode of operation is to be converted from motoring to generating.
Claim 8
Dependent Claim
29 words
The excitation system according to claim 1 wherein said exciter field windings are connected in a three phase WYE connection and have a three phase excitation voltage applied thereto
Claim 9
Dependent Claim
103 words
The excitation system according to claim 1 including a plurality of switch means coupled between said polyphase field windings and a source of polyphase voltage, further switch means to connecT a DC voltage to said windings, and means to actuate said plurality of switch means and to disable said further switch means when said dynamoelectric machine is operated as a motor and means to disable said plurality of switches and enable said further switch means when the dynamoelectric machine reaches a predetermined speed whereby the polyphase voltage is disconnected and the DC voltage is connected to the field windings during the generating mode.
Claim 10
Dependent Claim
71 words
The excitation system according to claim 4 wherein said switch means and said further switch means include gate controlled solid state switches, and means for selectively applying triggering signals to the gate electrodes of said plurality of switches during the motoring mode, speed responsive means for removing triggering signals from the said plurality solid state switches and triggering said further solid state switch when the dynamoelectric machine reaches a predetermined speed.
Claim 11
Dependent Claim
54 words
The excitation system according to claim 1 including a permanent magnet generator mounted on the same shaft as said dynamoelectric machine, means to rectify the output of said permanent magnet generator, and switching means to impress the rectified output voltage on the said field windings when the dynamoelectric machine is driven as a generator.
Claim 12
Dependent Claim
24 words
The excitation system according to claim 5 wherein each of said plurality of switching means comprises a pair of oppositely poled silicon controlled rectifiers.
Claim 13
Dependent Claim
100 words
The excitation system according to claim 1 wherein said field winding includes three winding sections, two of said winding sections being permanently connected, a first switch means for connecting one end of the remaining winding section to the junction of the permanently connected winding sections to connect the field windings in a polyphase connection during motor operation of the dynamoelectric machine, and further switch means to connect said one end of the remaining winding to the remaining end of one of said permanently connected winding sections to connect the field windings in series during generator operation of the dynamoelectric machine.
References Cited (Backward Citations)
US3591844A
Cited
US3764815A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |