Overvoltage Protection of Thyristors and Thyristor Modules

This paper presents a design approach for protective RC circuits for thyristors and thyristor modules used in power electronic converters. The study focuses on limiting overvoltages caused by transients, resonant phenomena, and inductive switching, which pose a threat to the reliability of thyristors. A mathematical model is developed to determine the parameters of the protective circuit under the assumption of periodic transient processes. In the numerical analysis, the overvoltage coefficient k_s (surge factor), ranging from 0.9 to 1.5, is used to calculate permissible values for resistance and capacitance. The obtained results are reduced to standard component values (E24 and μF series), ensuring practical applicability in industrial conditions. Visualization using 3D graphs and heatmaps allows for clear values in the range of 1.2-1.4 provide an optimal compromise between efficiency and component availability. The proposed methodology contributes to improving the operational robustness of thyristor systems.