Angle-based speed estimation of alternating current machines utilizing a median filter

Ali Mohamad Bazzi (Inventor), Philip T Krein (Inventor)

Research output: Patent


A computer-implemented method for estimating a rotor speed of an alternating current (AC) machine is provided. The method includes determining a stator flux signal based on signals of voltage and current inputs to the AC machine, and determining a rotor flux signal of the AC machine based on the determined stator flux signal. The method includes determining an electrical angle signal based on the determined rotor flux signal, and deriving an electrical frequency signal from the determined electrical angle signal. Subsequently, the method includes sampling the derived electrical frequency signal at a predetermined sampling rate, and storing a predetermined number of sample values. The method further includes evaluating a median value of the predetermined set of electrical frequency sample values, determining a slip frequency value of the AC machine, and determining the rotor speed of the AC machine by subtracting the slip frequency value from the electrical frequency median value.
Original languageEnglish (US)
U.S. patent number9954624
Filing date3/15/13
StatePublished - Apr 24 2018


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