Steady-State Analysis of the Series Resistance-Inductance Circuit with Controlled Switches

The effect of forced-commutation on the ac phase controller with a series resistance-inductance load has been investigated. It has been shown that the total circuit power factor can exceed that of the load to sinusoidal current, with selected firing angles. Two modes of switching are introduced in which one maintains the fundamental power factor to near unity despite the load being largely inductive. In the second the fundamental power factor is kept to its most leading value and a relative improvement in distortion factor is achieved.