Prediction and recovery of zero-crossing information and selective control signal pulse duration

Abstract

Operation of an electrical load controller includes predetermining a duration of time based at least in part on a frequency of an alternating current (AC) waveform, the AC waveform oscillating though full cycles, selecting a detection window of time equal in duration to the predetermined duration of time, the selected detection window extending from a selected first time to a selected second time and straddling an expected time of a next zero-crossing of the AC waveform, monitoring a zero-crossing signal for a zero-crossing indication, of the next zero-crossing, occurring within the selected detection window, ascertaining a time of the next zero-crossing based on the monitoring, and selectively controlling a supply of AC power to a load, wherein the controlling uses the ascertained time of the next zero-crossing of the AC waveform to fire a switching circuit of the electrical load controller.