Experimental and Simulation Study of Parallel-Connected Thyristors in Impact-Ionization Switching Mode

This article investigates the impact-ionization switching mechanism in parallel-connected high-voltage thyristors, aiming to bridge the gap between experimental observations and numerical simulations. A novel experimental setup is designed to study four parallel thyristors triggered in impact-ionization wave mode, marking the first instance of such an arrangement. In addition to the experiment, a numerical simulation is used to assess the impact-ionization switching of high-voltage thyristors in parallel connection. The numerical simulation adopts a quasi-3-D model of the thyristor structure derived from a 2-D model, considering cylindrical symmetry. Three distinct scenarios are explored in the simulation: 1) static voltage breakdown; 2) suppression of unwanted ${d}V/{d}t$ triggering; and 3) delayed impact-ionization breakdown. The article presents a detailed comparison and discussion of the experimental and numerical simulation results related to impact-ionization switching.