# Investigation of Transient Thermal Behavior in Thyristors Under Pulse Conditions

## TL;DR

This paper studies how high-power thyristors behave under pulsed conditions, focusing on thermal and current distribution challenges.

## Contribution

The study introduces a 2D device–circuit co-simulation and a 3D finite element model to better understand thyristor behavior under pulsed loads.

## Key findings

- A velocity equation for thyristor current expansion was derived from simulation results.
- A generalized model for complex gate structures was developed to predict transient temperature distributions.
- Cycle surge life tests provided insights for optimizing thyristors in pulsed applications.

## Abstract

Under pulsed discharge conditions, high-power thyristors face challenges such as an excessively high current rise rate (di/dt) and the issue of triggering front expansion, which are difficult to accurately simulate. Traditional modeling approaches often neglect the non-uniform distribution and expansion process of the internal current within the silicon wafer. In this study, we address these limitations by incorporating these critical factors into our analysis. Using a two-dimensional device–circuit co-simulation approach, we investigate the current, temperature, and thermal power distribution within the thyristor during the turn-on process under pulsed discharge conditions. Based on the simulation results, we derive the velocity equation governing the transverse expansion of the thyristor current. Furthermore, we establish a three-dimensional finite element model of the thyristor and develop a generalized extended model for complex gate structures. These models enable us to obtain the transient temperature distribution during the thyristor turn-on process under pulsed conditions. Finally, we conduct cycle surge life tests on various types of thyristors, providing valuable insights for the selection and optimization of thyristors designed for pulsed applications.