Power control system

DETAILED DESCRIPTION In accordance with the state of the prior art, it may be said to have been the general objective of the present invention to produce a novel, solid-state, electronic controller suitable which can be programmed or controlled in analog fashion, and which provides simple and economical circuitry for the purpose.
Alternate half-cycles of an AC input signal are inherently time-phased, 180 electrical degrees and are handled in separate channels.
The aforementioned alternate half-cycles are first formed into separate trains of square waves which are converted to corresponding separate pulse sawtooth signal trains.
Comparators act as pick-off devices to initiate the corresponding series of gates of variable duration depending on the reference (external control) signal amplitude against which said comparators function.
Those variable gates control SCR electrical firing angle.
A power amplifier is provided for each channel to produce the required drive for SCR gate electrodes.
Since the SCR's are usually operating at relatively high voltages, optical isolators couple the variable gate signals to the power amplifiers, the latter being adapted to "float" electrically.
The power amplifiers introduce leading edge spikes for SCR "hard" turn-on and the ramp wave forms (pulsed sawtooth wave forms on pedestals) have linear slopes due to the particularly novel constant current characteristics of C-MOS solid state NAND circuit elements employed in their generation.
The apparatus is particularly adapted to AC induction motor starting control, but is also entirely suited for any analog programmed or manually controlled (at low level) operation for AC power varying control either intermittently or continuously.
The manner in which the invention is typically implemented will be evident as this description proceeds.