| 摘要 |
A system for controlling AC power for any load in which it is desired to limit and/or specifically program current at least for an initial period. SCR switches are employed, these being controlled as to angle of conduction out of the 180 degrees of each AC half cycle. The positive and negative half cycles are separated in a diode bridge and are separately handled throughout to the SCR's, which are connected two in parallel, in opposing polarity per phase. Voltage ramps are generated for each half cycle and a comparison circuit acts as a pick-off to start the SCR gate at a point in the half cycle determined by the comparator reference, the latter being the independent control. Fast turn-on leading edge spikes on the SCR gates are provided to minimize SCR di/dt stress.
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