US5023537A
Expired / Lapsed
US
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Low frequency feeder fault protection
Assignee: Sundstrand Corp
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Filing: 1989-08-23
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Granted: 1991-06-11
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Expires: 2009-08-23
Abstract
Abstract The problem of detecting low frequency faults is solved in a VSCF control system which is operated in a start mode to start an engine (18) using a brushless synchronous generator operating as a motor (12). The motor (12) receives power through a feeder (52) from a converter (36) which is coupled through an additional feeder (44) to a source (42) of AC power. During normal, non-fault conditions, the sum of the input currents to the converter (36) and the sum of the output currents from the converter (36) must each be zero. When a fault condition exists, then one or both of these currents will be non-zero, depending upon the location of the fault. A single current sensor (56) is used to sense feeder faults by positioning the sensor to read the current through the converter input feeder (44). As long as no feeder to ground fault condition exists, then the current sensor (44) senses zero current. If a non-zero current is sensed, then it is assumed that a fault condition exists.
Inventors
- 👤 Paul Baits
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:04
CPC Classifications
F; F02; F02N; F02N11/00; F02N11/04; H; H02; H02H; H02H3/00; H02H3/26; H02H3/32
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
179 words
In a start control for a polyphase brushless machine having a rotor and a stator having a polyphase stator coil which is controllably energized from a converter which develops regulated power from a source of unregulated AC power to impart rotation to the rotor, wherein the regulated power comprises relatively low-frequency power at start-up, a fault protection control comprising: an input feeder circuit comprising a conductor for each phase connecting the power source to said converter each conductor conducting low frequency current at start-up; an output feeder circuit comprising a conductor for each phase connecting said converter to the polyphase stator coil each conductor conducting low frequency current at start-up; a single current sensor operatively associated with all of the conductors of at least one of said feeder circuits to sense a sum of the low frequency currents through the conductors associated with the one of said feeder circuits; and means coupled to said sensing means for indicating a fault condition at start-up if the current sum sensed by said current sensor is greater than a select minimum level.
Claim 2
Dependent Claim
179 words
In a start control for a polyphase brushless machine having a rotor and a stator having a polyphase stator coil which is controllably energized from a converter which develops regulated power from a source of unregulated AC power to impart rotation to the rotor, wherein the regulated power comprises relatively low-frequency power at start-up, a fault protection control comprising: an input feeder circuit comprising a conductor for each phase connecting the power source to said converter each conductor conducting low frequency current at start-up; an output feeder circuit comprising a conductor for each phase connecting said converter to the polyphase stator coil each conductor conducting low frequency current at start-up; a single current sensor operatively associated with all of the conductors of at least one of said feeder circuits to sense a sum of the low frequency currents through the conductors associated with the one of said feeder circuits; and means coupled to said sensing means for indicating a fault condition at start-up if the current sum sensed by said current sensor is greater than a select minimum level.
Claim 3
Dependent Claim
17 words
The fault protection control of claim 1 wherein said current sensor comprises a Hall effect current sensor.
Claim 4
Dependent Claim
14 words
The fault protection control of claim 1 wherein said indicating means comprises a comparator.
Claim 5
Dependent Claim
42 words
The fault protection control of claim 1 wherein said current sensor is operatively associated with said input feeder circuit and said indicating means indicates a fault condition from any of said input feeder circuit conductors or output feeder circuit conductors to ground.
Claim 6
Dependent Claim
178 words
A start control for a motor having a rotor and a stator having a three phase stator coil comprising: a first feeder circuit comprising a conductor for each phase connectable to an unregulated three phase power source each conductor conducting low frequency current at start-up; a power converter coupled to said first feeder circuit for converting the unregulated three phase power to regulated three phase power, and including means for controlling the frequency of the regulated power in accordance with rotor speed; a second feeder circuit comprising a conductor for each phase connecting said power converter to the three phase stator coil each conductor conducting low frequency current at start-up; a current sensor operatively associated with all of the conductors of at least one of said feeder circuits to sense a sum of the low frequency currents through the conductors associated with the one of said feeder circuits; and means coupled to said sensing means for indicating a fault condition at start-up if the current sum sensed by said current sensor is greater than a select minimum level.
Claim 7
Dependent Claim
178 words
A start control for a motor having a rotor and a stator having a three phase stator coil comprising: a first feeder circuit comprising a conductor for each phase connectable to an unregulated three phase power source each conductor conducting low frequency current at start-up; a power converter coupled to said first feeder circuit for converting the unregulated three phase power to regulated three phase power, and including means for controlling the frequency of the regulated power in accordance with rotor speed; a second feeder circuit comprising a conductor for each phase connecting said power converter to the three phase stator coil each conductor conducting low frequency current at start-up; a current sensor operatively associated with all of the conductors of at least one of said feeder circuits to sense a sum of the low frequency currents through the conductors associated with the one of said feeder circuits; and means coupled to said sensing means for indicating a fault condition at start-up if the current sum sensed by said current sensor is greater than a select minimum level.
Claim 8
Dependent Claim
16 words
The start control of claim 5 wherein said current sensor comprises a Hall effect current sensor.
Claim 9
Dependent Claim
25 words
The start control of claim 5 wherein said indicating means comprises a comparator for indicating if said sensed current is above a selected minimum level.
Claim 10
Dependent Claim
42 words
The start control of claim 5 wherein said current sensor is operatively associated with said first feeder circuit and said indicating means indicates a fault condition from any of said first feeder circuit conductors or said second feeder circuit conductors to ground.
Claim 11
Dependent Claim
140 words
In a converter control for a polyphase motor which is controllably energized from a source of unregulated AC power connected through plural input feeder conductors to a converter, which is connected through plural output feeder conductors to the motor, to impart rotation to the rotor, and wherein the converter develops regulated power which comprises relatively low-frequency power at start-up, and said conductors conduct low frequency current at start-up, the improvement comprising: a single current sensor operatively associated with all of the conductors of at least one of said feeder circuits to sense a sum of the low frequency currents through the conductors associated with the one of said feeder circuits; and means coupled to said sensing means for indicating a fault condition at start-up if the current sum sensed by said current sensor is greater than a select minimum level.
Claim 12
Dependent Claim
140 words
In a converter control for a polyphase motor which is controllably energized from a source of unregulated AC power connected through plural input feeder conductors to a converter, which is connected through plural output feeder conductors to the motor, to impart rotation to the rotor, and wherein the converter develops regulated power which comprises relatively low-frequency power at start-up, and said conductors conduct low frequency current at start-up, the improvement comprising: a single current sensor operatively associated with all of the conductors of at least one of said feeder circuits to sense a sum of the low frequency currents through the conductors associated with the one of said feeder circuits; and means coupled to said sensing means for indicating a fault condition at start-up if the current sum sensed by said current sensor is greater than a select minimum level.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-06-10 | 1994-12-10 | 1995-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-06-10 | 1998-12-10 | 1999-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-06-10 | 2002-12-10 | 2003-06-11 | $7700.00 | Window Closed / Lapsed |