Patent US5528444A successfully refreshed from Google Patents.
US5528444A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic overvoltage protection for an alternator in a locomotive propulsion system
Assignee: General Electric Co
•
Filing: 1994-09-23
•
Granted: 1996-06-18
•
Expires: 2014-09-23
Abstract
Abstract A shorted diode protection system for a traction vehicle propulsion system including a synchronous generator having armature and field windings and a bridge rectifier circuit coupling the generator armature windings to a traction motor employs a normally non-conducting solid-state controllable electric valve in parallel with the generator field windings. When a rectifier diode of the bridge rectifier circuit fails short, an a-c current is reflected into the generator field winding circuit. Upon detection of this reflected current, the valve is switched into a conducting state, thereby limiting the voltage on the generator field windings.
Inventors
- 👤 Philip R. Cooke
- 👤 Joseph A. Laukaitis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 06:07
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/06; B; B60; B60L; B60L3/00; B60L3/0023; B60L3/003; B60L3/0061; B60L3/0069; B60L50/00; B60L50/50; B60L50/52; B60L2200/00; B60L2200/26; B60L2220/00; B60L2220/10; B60L2220/14; Y; Y02; Y02T; Y02T10/00; Y02T10/60; Y02T10/70
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
164 words
A shorted diode protection system for a traction vehicle propulsion system including at least one electric traction motor, a synchronous generator having armature and field windings, a controllable source of excitation current connected to the field windings, and electric power conditioning means interconnecting the armature windings to the traction motor, the power conditioning means including a bridge rectifier circuit for converting alternating current from the armature windings to direct current on a pair of relatively positive and negative output buses, the system comprising: detecting means for producing a gating signal in response to a reflected alternating current voltage appearing on the field windings in excess of a preselected magnitude; at least one solid-state controllable electric valve connected in parallel circuit arrangement with the field windings, said valve being normally non-conducting and being switchable to a conducting state by said gating signal applied to a gate terminal thereof; and means coupling said gating signal to said valve to limit the voltage on the field winding.
Claim 2
Dependent Claim
164 words
A shorted diode protection system for a traction vehicle propulsion system including at least one electric traction motor, a synchronous generator having armature and field windings, a controllable source of excitation current connected to the field windings, and electric power conditioning means interconnecting the armature windings to the traction motor, the power conditioning means including a bridge rectifier circuit for converting alternating current from the armature windings to direct current on a pair of relatively positive and negative output buses, the system comprising: detecting means for producing a gating signal in response to a reflected alternating current voltage appearing on the field windings in excess of a preselected magnitude; at least one solid-state controllable electric valve connected in parallel circuit arrangement with the field windings, said valve being normally non-conducting and being switchable to a conducting state by said gating signal applied to a gate terminal thereof; and means coupling said gating signal to said valve to limit the voltage on the field winding.
Claim 3
Dependent Claim
38 words
The shorted diode protection system of claim 1 and including a second controllable solid-state electric valve connected in parallel with said at least one valve, each of said valves being unidirectional devices and being coupled in inverse relationship.
Claim 4
Dependent Claim
16 words
The shorted diode protection system of claim 2 wherein each of said valves comprises an SCR.
Claim 5
Dependent Claim
29 words
The shorted diode protection system of claim 3 and including a thyrite connected in parallel with said field winding for dissipating transient voltages of less than said preselected magnitude.
Claim 6
Dependent Claim
19 words
The shorted diode protection system of claim 3 and including a snubber circuit coupled in parallel with the SCRs.
Claim 7
Dependent Claim
73 words
The shorted diode protection system of claim 1 wherein said detecting means comprises a solid-state rectifier circuit coupled to said field windings and adapted to produce a d-c voltage output proportional to an a-c voltage component on said field windings, a trigger circuit for producing a trigger pulse when the d-c voltage exceeds a preselected value, and means responsive to said trigger pulse for generating the gating signal for a predetermined time duration.
Claim 8
Dependent Claim
59 words
The shorted diode protection system of claim 6 wherein the means for generating the gating signal comprises a monostable multivibrator responsive to said trigger pulse for generating a signal of said predetermined time duration and a gate signal generator responsive to said multivibrator signal for supplying gating signals to said valve during the time duration of said multivibrator signal.
Claim 9
Dependent Claim
95 words
The shorted diode protection system of claim 1 and including: means for detecting a fault current in said armature windings; means connected in circuit with said field winding for commutating off said controllable source of excitation current upon detection of said fault current; means selectably connectable in circuit with said field winding for dissipating energy therein subsequent to commutation of said excitation source; and means for inhibiting operation of said detecting means for producing a gating signal upon detection of the reflected alternating current voltage on the field windings in excess of a preselected magnitude.
Claim 10
Dependent Claim
80 words
The shorted diode protection system of claim 1 and including: means for detecting a fault current in said armature windings; means connected in circuit with said field winding for commutating off said controllable source of excitation current upon detection of said fault current; means selectably connectable in circuit with said field winding for dissipating energy therein subsequent to commutation of said excitation source; and means for inhibiting operation of said fault current detecting means upon detection of the fault current.
Claim 11
Independent Claim
130 words
A method of protecting a synchronous generator from a reflected overvoltage condition in a system in which the generator has a field winding connected to a source of controllable excitation current and armature windings connected to a bridge rectifier for supplying direct current (dc) electric power, the reflected overvoltage being caused by a short-circuit condition in the rectifier causing a reflected alternating current to appear on the field winding, the method comprising the steps of: developing an output voltage representative of an alternating current voltage on the field winding; detecting when the alternating current voltage exceeds a preselected maximum magnitude and generating a fault signal in response thereto; and short-circuiting the field winding in response to the fault signal while continuing to energize the bridge rectifier from the armature windings.
Claim 12
Independent Claim
130 words
A method of protecting a synchronous generator from a reflected overvoltage condition in a system in which the generator has a field winding connected to a source of controllable excitation current and armature windings connected to a bridge rectifier for supplying direct current (dc) electric power, the reflected overvoltage being caused by a short-circuit condition in the rectifier causing a reflected alternating current to appear on the field winding, the method comprising the steps of: developing an output voltage representative of an alternating current voltage on the field winding; detecting when the alternating current voltage exceeds a preselected maximum magnitude and generating a fault signal in response thereto; and short-circuiting the field winding in response to the fault signal while continuing to energize the bridge rectifier from the armature windings.
Claim 13
Dependent Claim
37 words
The method of claim 10 wherein the step of short-circuiting includes the steps of: connecting a solid-state controllable electric switch in parallel with the field windings; and gating the switch into conduction for a predetermined time duration.
Claim 14
Dependent Claim
35 words
The method of claim 11 wherein the switch comprises a pair of inversely connected SCR's and the step of gating comprises applying gate pulses to gate terminals of the SCR's for the predetermined time duration.
Claim 15
Dependent Claim
44 words
The method of claim 12 and including the steps of: monitoring the armature windings for an overcurrent condition; connecting commutating means across the field windings in response to a monitored overcurrent; and inhibiting application of gate pulses to the SCR's during the overcurrent condition.
Claim 16
Dependent Claim
62 words
The method of claim 13 wherein the bridge rectifier is coupled to supply d-c electric power to at least one solid-state inverter, the inverter having a plurality of controllable electric valves for converting the d-c power to a-c power at a selected frequency, and wherein the step of monitoring includes the step of detecting overcurrent through the inverter from a shorted valve.
Claim 17
Dependent Claim
26 words
The method of claim 12 and including the step of dissipating transient voltage on the field through a thyrite coupled in parallel with the field windings.
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) | 1999-06-18 | 1999-12-18 | 2000-06-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-06-18 | 2003-12-18 | 2004-06-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-06-18 | 2007-12-18 | 2008-06-18 | $7700.00 | Window Closed / Lapsed |