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Method of detecting system function by measuring frequency response

United States Patent

July 1, 2008
View the Complete Patent at the US Patent & Trademark Office
Method and Apparatus for In-Situ Real Time Characterization of Energy Storage and Energy Conversion Devices
Real time battery impedance spectrum is acquired using one time record, Compensated Synchronous Detection (CSD). This parallel method enables battery diagnostics. The excitation current to a test battery is a sum of equal amplitude sin waves of a few frequencies spread over range of interest. The time profile of this signal has duration that is a few periods of the lowest frequency. The voltage response of the battery, average deleted, is the impedance of the battery in the time domain. Since the excitation frequencies are known, synchronous detection processes the time record and each component, both magnitude and phase, is obtained. For compensation, the components, except the one of interest, are reassembled in the time domain. The resulting signal is subtracted from the original signal and the component of interest is synchronously detected. This process is repeated for each component.
Morrison; John L. (Butte, MT), Morrison; William H. (Manchester, CT)
Montana Tech of the University of Montana (Butte, MT)
11/ 825,629
July 5, 2007
The subject invention was made with government support under a research project supported by NASA, Grant No. NNA05AC24C. The government has certain rights in this invention.