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

Claim 22:
23. 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, the output signal comprising a plurality of pulses during each of which the output signal remains in an active state; 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;
determining one or more pulse widths of a corresponding one or more pulses of the plurality of pulses, each pulse width of the one or more pulse widths indicating timing between a respective pair of consecutive zero-crossings of the input signal waveform;
determining a half-cycle time corresponding to the one or more pulse widths, the half-cycle time representing duration of half-cycles of the input signal waveform;
adjusting the half-cycle time using the at least one time offset to provide a duration of half-cycles of the input AC waveform; and
determining a frequency of the input AC waveform using the adjusted half-cycle time.