Patent ID: 11871493
Assignee: LEVITON MANUFACTURING CO., INC.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 21:
22. An electrical load controller for controlling conduction of a supply of alternating current (AC) power to a load, the supply of AC power having an input AC waveform, the input AC waveform comprising zero-crossings between positive and negative half-cycles of the input AC waveform, and the electrical load controller comprising:
a line input terminal and a load output terminal, the line input terminal configured to be electrically coupled to the supply of AC power and receive the input AC waveform thereof, and the load output terminal configured to be electrically coupled to the load;
a switching circuit electrically coupled in series between the line input terminal and the load output terminal, the switching circuit having an ON state in which the switching circuit conducts the supply of AC power to the load, and an OFF state in which the switching circuit does not conduct the supply of AC power to the load;
a zero-crossing detector circuit configured to receive an input signal waveform, representative of the input AC waveform, at an input of the zero-crossing detector circuit and to output an output signal from an output of the zero-crossing detector circuit; and
a microcontroller, the microcontroller configured to receive from the zero-crossing detector circuit the output signal therefrom, and to perform:
obtaining at least one time offset, the at least one time offset representing amounts of time between (i) zero-crossings of the input signal waveform at the input of the zero-crossing detector circuit and (ii) corresponding transitions of the output signal from the output of the zero-crossing detector circuit to the microcontroller, each of the corresponding transitions corresponding to a respective zero-crossing of the zero-crossings of the input signal waveform and indicating a respective zero-crossing of the input AC waveform; and
determining times of the zero-crossings of the input AC waveform, the determining the times of the zero-crossings of the input AC waveform comprising:
determining times of the corresponding transitions as detected by the microcontroller; and
adjusting the determined times of the corresponding transitions to produce the times of the zero-crossings of the input AC waveform, wherein the adjusting uses the at least one time offset.