Processor module for power factor controller

Claim 1

In a motor control circuit for an electric motor connected to a source of voltage, means for producing a first waveform signal representative of the voltage, means for producing a second waveform signal representative of the motor current, sample and hold means responsive to said first and second waveform signals for producing a voltage signal proportional to the phase difference between said first and second waveform signals and for holding said voltage signal, said sample and hold means including an analog switch having a gate portion and a switch portion, said sample and hold means further including capacitance means connected to said switch portion for responding to the voltage of, and thus sampling, said second waveform signal only when said switch portion is conductive, means for applying said first waveform signal to said gate portion, means for applying said second waveform signal to said switch portion, differentiating means for periodically ramping said first waveform signal to ground, said switch portion comprising means becoming conductive only when said first waveform signal has been ramped to ground, and means responsive to the voltage held by said capacitance for controlling the firing of a solid state switch in circuit with said source.