Electrical Losses in Semiconductor Devices during Control of the Processes

Electrical losses are significant for the normal work of semiconductor devices (diodes, transistors, thyristors, symistors (triaks), dynistors, etc In this paper, the phase control of a thyristor circuit activated by an AC voltage source with varying frequencies is analyzed. The formulas for the average $I_{av}$ and the effective $I_{RMS}$ values of the current and the average power $P_{av}$ as functions of the firing angle $\alpha $ and a frequency $f$ have been worked out. Criterion for determining the maximum admissible firing angle $\alpha $ of the thyristors in case of different frequencies has been suggested. The paper finishes with conclusion remarks for the AC supply voltage stabilization in phase control of the average value of the AC current flowing through a load.