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

Abstract

Operating an electrical load controller includes determining a firing angle at which to fire a switching circuit of the electrical load controller and selecting a control signal pulse duration between a fixed duration and a variable duration based on the firing angle and on whether voltage sag is present in an alternating current (AC) waveform, then controlling a supply of AC power to a load based on the selected duration. An electrical load controller and method of operating such is also provided, in which a detection window is selected for detecting zero-crossings (ZC) of an AC waveform, a ZC signal is monitored and a time of a next ZC is ascertained, and a supply of AC power to a load is controlled using the ascertained time.