Adaptive, on line, statistical method and apparatus for detection of broken bars in motors by passive motor current monitoring and digital torque estimation
April 1, 2016. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesRotor fault detector for induction motors Method of detecting change using image Spectral analysis of induction motor current to detect rotor faults with reduced false alarms Character and phoneme recognition based on probability clustering Apparatus for generating a feature matrix based on normalized out-class and in-class variation matrices Method for incipient failure detection in electric machines Electrical distribution equipment with torque estimating capability Object inspection method employing selection of discerning features using mahalanobis distances Turn fault detection Stator turn fault detector for AC motor InventorsApplicationNo. 627721 filed on 04/01/1996US Classes:702/185, Cause or fault identification324/76.11, MEASURING, TESTING, OR SENSING ELECTRICITY, PER SE324/76.19, Frequency spectrum analyzer324/545, Armature or rotor324/772, Motor or generator fault tests361/23, Motor protective condition responsive circuits361/30, Current and voltage361/31CurrentExaminersPrimary: Trammell, James P.Assistant: Dam, Tuan Q. Attorney, Agent or FirmInternational ClassesG01R 023/00G05B 013/00 AbstractDuring a learning stage a motor current signal is monitored, and estimated motor torque is used to transform the current signal into a time-frequency spectra including a plurality of segments representative of good operating modes. A representative parameter and a respective boundary of each segment is estimated. The current signal is monitored during a test stage to obtain test data, and the test data is compared with the representative parameter and the respective boundary of each respective segment to detect the presence of a fault in a motor. Frequencies at which broken bar faults are likely to occur in a motor can be estimated using the estimated motor torque, and a weighting function can highlight such frequencies during estimation of the parameter. The current signal can be further subdivided into the segments by monitoring sidebands of the frequency components of current spectrum strips of each segment. Estimating the parameter and the boundary of each segment can include calculating a segment mean (the representative parameter) and variance for each frequency component in each respective segment; calculating a modified Mahalanobis distance for each strip of each respective segment; and for each respective segment, using respective modified Mahalanobis distances to calculate a respective radius about a respective segment mean to define the respective boundary.Other References
Field of SearchMotor or generator fault testsOf electrically operated apparatus (power tool, appliance, machine, etc.) Of electrically operated apparatus (power tool, appliance, machine, etc.) Armature or rotor MEASURING, TESTING, OR SENSING ELECTRICITY, PER SE Frequency spectrum analyzer Determining both similarities and differences Cluster analysis Statistical decision process Synchronized or sequential opening or closing Motor protective condition responsive circuits Current and voltage Current | |
