DIFFERENTIAL SENSOR APPARATUS AND METHOD FOR LAMINATED CORE FAULT DETECTION
First Claim
1. A method for detecting faults in a laminated core of an electric machine, comprising:
- (a)positioning a pair of magnetic flux injection yokes near at least one tooth of the core, the yokes being arranged side-by-side in close proximity to each other, each yoke having a pair of flux injecting arm portions and each yoke being wound with a magnetic flux excitation winding and having a flux sensor on at least one of the arm portions;
(b)supplying current to the flux injection winding of at least one yoke to inject magnetic flux into the at least one tooth of the core;
(c)measuring a flux difference signal obtained between two adjacent flux sensors, each flux sensor of the two sensors from which the difference signal is obtained being located on a different yoke; and
(d)using the measured flux difference signal to detect a core lamination fault.
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Accused Products
Abstract
A differential probe is scanned along a stator core tooth portion to detect lamination faults. The probe utilizes two magnetic flux injection yokes arranged side-by-side in relatively close proximity, each yoke having two arm portions and two core-tooth flux-injection surfaces, each yoke being wound with an excitation coil winding and at least one yoke-arm of each yoke having a magnetic flux sensor. Current is supplied to the excitation coil windings on each yoke to inject magnetic flux into the stator core laminations while the probe is moved in a scanning process along the core teeth across the laminations. The magnetic flux differential detected at adjacent regions in the core by flux sensors on each of the two yokes is used to incrementally evaluate the core for laminations faults. The output produced by the differential probe may be converted to a digital signal and provided to a computer system for storage and future analysis.
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Citations
21 Claims
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1. A method for detecting faults in a laminated core of an electric machine, comprising:
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(a)positioning a pair of magnetic flux injection yokes near at least one tooth of the core, the yokes being arranged side-by-side in close proximity to each other, each yoke having a pair of flux injecting arm portions and each yoke being wound with a magnetic flux excitation winding and having a flux sensor on at least one of the arm portions;
(b)supplying current to the flux injection winding of at least one yoke to inject magnetic flux into the at least one tooth of the core;
(c)measuring a flux difference signal obtained between two adjacent flux sensors, each flux sensor of the two sensors from which the difference signal is obtained being located on a different yoke; and
(d)using the measured flux difference signal to detect a core lamination fault. - View Dependent Claims (2, 3, 4, 5)
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6. A test probe apparatus for detecting faults in a laminated core of an electric machine, comprising:
at least two magnetic flux injection yokes arranged side-by-side in close proximity, each yoke comprising at least two arm portions having a flux-injection surface at an end of each arm, each yoke being wound with an excitation winding and at least one arm portion of each yoke having a magnetic flux sensor affixed near the flux-injection surface. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. A system for detecting faults in a laminated core of an electric machine, comprising:
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a flux differential detecting magnetic flux-injection test probe device, said probe injecting a magnetic flux into at least two closely spaced adjacent regions of the core and producing a flux difference signal indicative of a difference in magnetic flux detected between the two closely spaced adjacent core regions;
a current source for supplying an electrical drive current to the probe;
a current source sensor for detecting a driving current supplied to the probe and producing a digital signal indicative of the driving current;
a differential flux signal detector connected to the probe for detecting the flux difference signal and producing a digital signal indicative of the flux difference; and
a computer receiving digital signals from the differential flux signal detector and the current source sensor for using the digital signals to detect core faults. - View Dependent Claims (16, 17)
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18. A method for detecting faults in a laminated core of an electric machine, comprising:
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(a) injecting a magnetic flux through at least one core tooth into a pair of closely spaced adjacent regions of the core;
(b) measuring a flux difference between said adjacent regions of the core;
(c) repeating (a) and (b) at incrementally different positions spaced along the core tooth; and
(e) using flux difference measurements obtained in (b) to detect core lamination faults. - View Dependent Claims (19, 20, 21)
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Specification