US5612629A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System and method for detecting fault conditions in a direct current motor
Assignee: Lockheed Martin Corp
•
Filing: 1995-06-07
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Granted: 1997-03-18
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Expires: 2015-06-07
Abstract
Abstract Apparatus and method are provided for determining indicating if certain types of circuit failures have occurred in a D.C. motor circuit such as a locked rotor condition, a short-circuit or an open circuit. The method includes the steps of, and the apparatus involves, applying a voltage to two leads of the D.C. motor sufficient to cause motor rotation, determining if flyback exists, determining if back EMF exists, and, finally, if a back EMF does not exist and flyback does exist then indicating a locked rotor condition. However, if a back EMF does not exist and flyback does not exist then an indication is provided that either an open-circuit or short-circuit condition exists. The same apparatus and method can be used with a voltage not sufficient to cause motor rotation, although given this limitation only flyback can be detected, so that only an open-circuit or short-circuit condition can be indicated.
Inventors
- 👤 Eugene T. Mullin
- 👤 Clifford J. Bader
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:02
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/08; H02H7/0833; H02H7/0838; G; G01; G01R; G01R31/00; G01R31/34; G01R31/343; H02P; H02P29/00; H02P29/02; H02P29/024; H02P29/0241
Claims Analysis
Total Claims: 62
Claim 1
Independent Claim
114 words
A method for detecting a fault condition of a locked rotor condition in a D.C. motor circuit having two voltage leads comprising the steps of: a) applying a voltage to the D.C. motor by way of the two voltage leads, wherein the voltage is sufficient to cause motor rotation, b) determining if flyback exists on the two voltage leads upon interruption of the applied voltage, c) before, during or after said step of determining if flyback exists, determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage, and d) indicating a locked rotor condition exists when the back EMF does not exist and the flyback does exist.
Claim 2
Independent Claim
114 words
A method for detecting a fault condition of a locked rotor condition in a D.C. motor circuit having two voltage leads comprising the steps of: a) applying a voltage to the D.C. motor by way of the two voltage leads, wherein the voltage is sufficient to cause motor rotation, b) determining if flyback exists on the two voltage leads upon interruption of the applied voltage, c) before, during or after said step of determining if flyback exists, determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage, and d) indicating a locked rotor condition exists when the back EMF does not exist and the flyback does exist.
Claim 3
Dependent Claim
19 words
A method as recited in claim 1 wherein the interruption is a temporary, brief interruption of the applied voltage.
Claim 4
Dependent Claim
16 words
A method as recited in claim 1, further comprising repeating steps a), b), c) and d).
Claim 5
Dependent Claim
43 words
A method as recited in claim 1 wherein said step of determining if a back EMF exists comprises determining if a back EMF exists on the two voltage leads after interruption of the applied voltage and at least partial decay of the flyback.
Claim 6
Dependent Claim
26 words
A method as recited in claim 1, further comprising the step of indicating normal motor condition exists when the back EMF exists and the flyback exists.
Claim 7
Dependent Claim
64 words
A method as recited in claim 1 wherein: said step of applying a voltage comprises alternately applying and removing a voltage, said step of determining if flyback exists comprises determining if flyback exists upon each removal of the applied voltage, and said step of determining if a back EMF exists comprises determining if a back EMF exists upon each removal of the applied voltage.
Claim 8
Dependent Claim
16 words
A method as recited in claim 1 wherein the D.C. motor is a brush-commutated D.C. motor.
Claim 9
Dependent Claim
15 words
A method as recited in claim 1 wherein the applied voltage comprises a voltage waveform.
Claim 10
Dependent Claim
61 words
A method as recited in claim 1 wherein said step of determining if flyback exists comprises the steps of: comparing the instantaneous voltage across the motor with a predetermined reference value, and during interruption of the applied voltage, producing a signal indicative of whether the instantaneous voltage across the motor exceeds the predetermined reference value and thus whether flyback is present.
Claim 11
Dependent Claim
43 words
A method as recited in claim 1 wherein said step of determining if flyback exists on the two voltage leads upon interruption of the applied voltage comprises determining if instantaneous flyback exists on the two voltage leads upon interruption of the applied voltage.
Claim 12
Dependent Claim
46 words
A method as recited in claim 1 wherein said step of determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage comprises determining if instantaneous back EMF exists on the two voltage leads during interruption of the applied voltage.
Claim 13
Independent Claim
122 words
A method for detecting a fault condition of one of an open-circuit condition or short-circuit condition in a D.C. motor circuit having two voltage leads comprising the steps of: a) applying a voltage to the D.C. motor by way of the two voltage leads, wherein the voltage is sufficient to cause motor rotation, b) determining if flyback exists on the two voltage leads upon interruption of the applied voltage, c) before, during or after said step of determining if flyback exists, determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage, and d) indicating one of an open-circuit or short-circuit condition exists when the back EMF does not exist and the flyback does not exist.
Claim 14
Independent Claim
122 words
A method for detecting a fault condition of one of an open-circuit condition or short-circuit condition in a D.C. motor circuit having two voltage leads comprising the steps of: a) applying a voltage to the D.C. motor by way of the two voltage leads, wherein the voltage is sufficient to cause motor rotation, b) determining if flyback exists on the two voltage leads upon interruption of the applied voltage, c) before, during or after said step of determining if flyback exists, determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage, and d) indicating one of an open-circuit or short-circuit condition exists when the back EMF does not exist and the flyback does not exist.
Claim 15
Dependent Claim
19 words
A method as recited in claim 12 wherein the interruption is a temporary, brief interruption of the applied voltage.
Claim 16
Dependent Claim
16 words
A method as recited in claim 12, further comprising repeating steps a), b), c) and d).
Claim 17
Dependent Claim
43 words
A method as recited in claim 12 wherein said step of determining if a back EMF exists comprises determining if a back EMF exists on the two voltage leads after interruption of the applied voltage and at least partial decay of the flyback.
Claim 18
Dependent Claim
26 words
A method as recited in claim 12, further comprising the step of indicating normal motor condition exists when the back EMF exists and the flyback exists.
Claim 19
Dependent Claim
64 words
A method as recited in claim 12 wherein: said step of applying a voltage comprises alternately applying and removing a voltage, said step of determining if flyback exists comprises determining if flyback exists upon each removal of the applied voltage, and said step of determining if a back EMF exists comprises determining if a back EMF exists upon each removal of the applied voltage.
Claim 20
Dependent Claim
16 words
A method as recited in claim 12 wherein the D.C. motor is a brush-commutated D.C. motor.
Claim 21
Dependent Claim
15 words
A method as recited in claim 12 wherein the applied voltage comprises a voltage waveform.
Claim 22
Dependent Claim
61 words
A method as recited in claim 12 wherein said step of determining if flyback exists comprises the steps of: comparing the instantaneous voltage across the motor with a predetermined reference value, and during interruption of the applied voltage, producing a signal indicative of whether the instantaneous voltage across the motor exceeds the predetermined reference value and thus whether flyback is present.
Claim 23
Dependent Claim
43 words
A method as recited in claim 12 wherein said step of determining if flyback exists on the two voltage leads upon interruption of the applied voltage comprises determining if instantaneous flyback exists on the two voltage leads upon interruption of the applied voltage.
Claim 24
Dependent Claim
46 words
A method as recited in claim 12 wherein said step of determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage comprises determining if instantaneous back EMF exists on the two voltage leads during interruption of the applied voltage.
Claim 25
Independent Claim
128 words
A system for detecting a fault condition of a locked rotor condition in a D.C. motor circuit having two voltage leads comprising: a) means for applying a voltage to the D.C. motor by way of the two voltage leads, wherein the voltage is sufficient to cause motor rotation, b) means for determining if flyback exists on the two voltage leads upon interruption of the applied voltage, c) means for determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage, and d) means, responsive to said means for determining if flyback exists and to said means for determining if a back EMF exists, for indicating a locked rotor condition exists when the back EMF does not exist and the flyback does exist.
Claim 26
Independent Claim
128 words
A system for detecting a fault condition of a locked rotor condition in a D.C. motor circuit having two voltage leads comprising: a) means for applying a voltage to the D.C. motor by way of the two voltage leads, wherein the voltage is sufficient to cause motor rotation, b) means for determining if flyback exists on the two voltage leads upon interruption of the applied voltage, c) means for determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage, and d) means, responsive to said means for determining if flyback exists and to said means for determining if a back EMF exists, for indicating a locked rotor condition exists when the back EMF does not exist and the flyback does exist.
Claim 27
Dependent Claim
45 words
A system as recited in claim 23 wherein said means for determining if a back EMF exists comprises means for determining if a back EMF exists on the two voltage leads after interruption of the applied voltage and at least partial decay of the flyback.
Claim 28
Dependent Claim
23 words
A system as recited in claim 23 wherein said means for applying a voltage comprises means for alternately applying and removing a voltage.
Claim 29
Dependent Claim
16 words
A system as recited in claim 23 wherein the D.C. motor is a brush-commutated D.C. motor.
Claim 30
Dependent Claim
15 words
A system as recited in claim 23 wherein the applied voltage comprises a voltage waveform.
Claim 31
Dependent Claim
61 words
A system as recited in claim 23 wherein said means for determining if flyback exists comprises: means for comparing instantaneous voltage across the motor with a predetermined reference value, and means for, during interruption of the applied voltage, producing a signal indicative of whether the instantaneous voltage across the motor exceeds the predetermined reference value and thus whether flyback is present.
Claim 32
Dependent Claim
45 words
A system as recited in claim 23 wherein said means for determining if flyback exists on the two voltage leads upon interruption of the applied voltage comprises means for determining if instantaneous flyback exists on the two voltage leads upon interruption of the applied voltage.
Claim 33
Independent Claim
135 words
A system for detecting a fault condition of one of an open-circuit or short-circuit condition in a D.C. motor circuit having two voltage leads comprising: a) means for applying a voltage to the D.C. motor by way of the two voltage leads, wherein the voltage is sufficient to cause motor rotation, b) means for determining if flyback exists on the two voltage leads upon interruption of the applied voltage, c) means for determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage, and d) means, responsive to said means for determining if flyback exists and to said means for determining if a back EMF exists, for indicating one of an open-circuit or short-circuit condition exists when the back EMF does not exist and the flyback does not exist.
Claim 34
Independent Claim
135 words
A system for detecting a fault condition of one of an open-circuit or short-circuit condition in a D.C. motor circuit having two voltage leads comprising: a) means for applying a voltage to the D.C. motor by way of the two voltage leads, wherein the voltage is sufficient to cause motor rotation, b) means for determining if flyback exists on the two voltage leads upon interruption of the applied voltage, c) means for determining if a back EMF exists on the two voltage leads upon interruption of the applied voltage, and d) means, responsive to said means for determining if flyback exists and to said means for determining if a back EMF exists, for indicating one of an open-circuit or short-circuit condition exists when the back EMF does not exist and the flyback does not exist.
Claim 35
Dependent Claim
45 words
A system as recited in claim 30 wherein said means for determining if a back EMF exists comprises means for determining if a back EMF exists on the two voltage leads after interruption of the applied voltage and at least partial decay of the flyback.
Claim 36
Dependent Claim
23 words
A system as recited in claim 30 wherein said means for applying a voltage comprises means for alternately applying and removing a voltage.
Claim 37
Dependent Claim
16 words
A system as recited in claim 30 wherein the D.C. motor is a brush-commutated D.C. motor.
Claim 38
Dependent Claim
15 words
A system as recited in claim 30 wherein the applied voltage comprises a voltage waveform.
Claim 39
Dependent Claim
61 words
A system as recited in claim 30 wherein said means for determining if flyback exists comprises: means for comparing instantaneous voltage across the motor with a predetermined reference value, and means for, during interruption of the applied voltage, producing a signal indicative of whether the instantaneous voltage across the motor exceeds the predetermined reference value and thus whether flyback is present.
Claim 40
Dependent Claim
45 words
A system as recited in claim 30 wherein said means for determining if flyback exists on the two voltage leads upon interruption of the applied voltage comprises means for determining if instantaneous flyback exists on the two voltage leads upon interruption of the applied voltage.
Claim 41
Independent Claim
119 words
A method for detecting a fault condition in a D.C. motor circuit having two electrical input leads, the method comprising the steps of: a) applying an electrical input to the D.C. motor by way of the two electrical input leads, wherein the electrical input is sufficient to cause motor rotation, b) determining if flyback exists on the two electrical input leads upon interruption of the applied electrical input, c) before, during or after said step of determining if flyback exists, determining if a back EMF exists on the two electrical input leads upon interruption of the applied electrical input, and d) indicating a locked rotor condition exists when the back EMF does not exist and the flyback does exist.
Claim 42
Independent Claim
119 words
A method for detecting a fault condition in a D.C. motor circuit having two electrical input leads, the method comprising the steps of: a) applying an electrical input to the D.C. motor by way of the two electrical input leads, wherein the electrical input is sufficient to cause motor rotation, b) determining if flyback exists on the two electrical input leads upon interruption of the applied electrical input, c) before, during or after said step of determining if flyback exists, determining if a back EMF exists on the two electrical input leads upon interruption of the applied electrical input, and d) indicating a locked rotor condition exists when the back EMF does not exist and the flyback does exist.
Claim 43
Dependent Claim
33 words
A method as recited in claim 37, further comprising the step of: indicating presence of an open-circuit or short-circuit condition when the back EMF does not exist and the flyback does not exist.
Claim 44
Dependent Claim
20 words
A method as recited in claim 37 wherein the interruption is a temporary, brief interruption of the applied electrical input.
Claim 45
Dependent Claim
16 words
A method as recited in claim 37, further comprising repeating steps a), b), c) and d).
Claim 46
Dependent Claim
45 words
A method as recked in claim 37 wherein said step of determining if a back EMF exists comprises determining if a back EMF exists on the two electrical input leads after interruption of the applied electrical input and at least partial decay of the flyback.
Claim 47
Dependent Claim
26 words
A method as recited in claim 37, further comprising the step of indicating normal motor condition exists when the back EMF exists and the flyback exists.
Claim 48
Dependent Claim
65 words
A method as recited in claim 37 wherein: said step of applying an electrical input comprises alternately applying and removing a voltage, said step of determining if flyback exists comprises determining if flyback exists upon each removal of the applied voltage, and said step of determining if a back EMF exists comprises determining if a back EMF exists upon each removal of the applied voltage.
Claim 49
Dependent Claim
16 words
A method as recited in claim 37 wherein the D.C. motor is a brush-commutated D.C. motor.
Claim 50
Dependent Claim
16 words
A method as recited in claim 37 wherein the applied electrical input comprises a voltage waveform.
Claim 51
Dependent Claim
76 words
A method as recited in claim 37 wherein said step of determining if flyback exists comprises the steps of: comparing the instantaneous electrical output from the motor on the two electrical input leads with a predetermined reference value, and during interruption of the applied electrical input, producing a signal indicative of whether the instantaneous electrical output from the motor on the two electrical input leads exceeds the predetermined reference value and thus whether flyback is present.
Claim 52
Dependent Claim
47 words
A method as recited in claim 37 wherein said step of determining if flyback exists on the two electrical input leads upon interruption of the applied electrical input comprises determining if instantaneous flyback exists on the two electrical input leads upon interruption of the applied electrical input.
Claim 53
Dependent Claim
50 words
A method as recited in claim 37 wherein said step of determining if a back EMF exists on the two electrical input leads upon interruption of the applied electrical input comprises determining if instantaneous back EMF exists on the two electrical input leads during interruption of the applied electrical input.
Claim 54
Independent Claim
131 words
A system for detecting a fault condition in a D.C. motor circuit having two electrical input leads comprising: a) means for applying an electrical input to the D.C. motor by way of the two electrical input leads, wherein the electrical input is sufficient to cause motor rotation, b) means for determining if flyback exists on the two electrical input leads upon interruption of the applied electrical input, c) means for determining if a back EMF exists on the two electrical input leads upon interruption of the applied electrical input, and d) means, responsive to said means for determining if flyback exists and to said means for determining if a back EMF exists, for indicating a locked rotor condition exists when the back EMF does not exist and the flyback does exist.
Claim 55
Independent Claim
131 words
A system for detecting a fault condition in a D.C. motor circuit having two electrical input leads comprising: a) means for applying an electrical input to the D.C. motor by way of the two electrical input leads, wherein the electrical input is sufficient to cause motor rotation, b) means for determining if flyback exists on the two electrical input leads upon interruption of the applied electrical input, c) means for determining if a back EMF exists on the two electrical input leads upon interruption of the applied electrical input, and d) means, responsive to said means for determining if flyback exists and to said means for determining if a back EMF exists, for indicating a locked rotor condition exists when the back EMF does not exist and the flyback does exist.
Claim 56
Dependent Claim
32 words
A system as recited in claim 49, further comprising: means for indicating existence of an open-circuit or short-circuit condition when the back EMF does not exist rand the flyback does not exist.
Claim 57
Dependent Claim
47 words
A system as recited in claim 49 wherein said means for determining if a back EMF exists comprises means for determining if a back EMF exists on the two electrical input leads after interruption of the applied electrical input and at least partial decay of the flyback.
Claim 58
Dependent Claim
24 words
A system as recited in claim 49 wherein said means for applying a electrical input comprises means for alternately applying and removing a voltage.
Claim 59
Dependent Claim
16 words
A system as recited in claim 49 wherein the D.C. motor is a brush-commutated D.C. motor.
Claim 60
Dependent Claim
16 words
A system as recited in claim 49 wherein the applied electrical input comprises a voltage waveform.
Claim 61
Dependent Claim
76 words
A system as recited in claim 49 wherein said means for determining if flyback exists comprises: means for comparing instantaneous electrical output from the motor on the two electrical input leads with a predetermined reference value, and means for, during interruption of the applied electrical input, producing a signal indicative of whether the instantaneous electrical output from the motor on the two electrical input leads exceeds the predetermined reference value and thus whether flyback is present.
Claim 62
Dependent Claim
48 words
A system as recited in claim 49 wherein said means for determining if flyback exists on the two electrical leads upon interruption of the applied electrical input comprises means for determining if instantaneous flyback exists on the two electrical input leads upon interruption of the applied electrical input.
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) | 2000-03-17 | 2000-09-16 | 2001-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-03-17 | 2004-09-16 | 2005-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-03-17 | 2008-09-16 | 2009-03-18 | $7700.00 | Window Closed / Lapsed |