Patent ID: 8204706
Filing Date: 2012-06-19
Classification: G01R

Abstract:
1. A method for continuously predicting a frequency of an input line power waveform of alternating current having a maximum value, a minimum value, and a reference point having a reference value on the waveform located between the maximum and minimum values, the method comprising the steps of: specifying an outer window defining a sense point on the waveform between a lower limit and an upper limit of the outer window, the sense point on the waveform being located a distance away from the reference point on the waveform, the sense point having a corresponding predicted sense point time; providing an inner window having an inner time interval less than an outer time interval corresponding to time between the lower limit and the upper limit; positioning the inner window at the predicted sense point time; identifying, using a computer processor, an actual sense point time of a measured inner sense point value of the sense point in the inner time interval and excluding one or more identified actual outer sense point values of the sense point being both outside of the inner time interval and within the outer time interval; and calculating, using the computer processor, the frequency of a future cycle of the waveform based on the actual sense point time.